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1. Evidence for Jet/Outflow Shocks Heating the Environment around the Class I Protostellar Source Elias 29: FAUST XXI

Author

Yoko Oya, Eri Saiga, Anna Miotello, Maria Koutoulaki, Doug Johnstone, Cecilia Ceccarelli, Claire J. Chandler, Claudio Codella, Nami Sakai, Eleonora Bianchi, Mathilde Bouvier, Steven Charnley, Nicolas Cuello, Marta De Simone, Logan Francis, Tomoyuki Hanawa, Izaskun Jiménez-Serra, Laurent Loinard, Francois Menard, Giovanni Sabatini, Charlotte Vastel, Ziwei Zhang, Yuri Aikawa, Felipe O. Alves, Nadia Balucani, Gemma Busquet, Paola Caselli, Emmanuel Caux, Spandan Choudhury, Francois Dulieu, Aurora Durán, Lucy Evans, Davide Fedele, Siyi Feng, Francesco Fontani, Tetsuya Hama, Eric Herbst, Shingo Hirano, Tomoya Hirota, Andrea Isella, Claudine Kahane, Bertrand Lefloch, Romane Le Gal, Hauyu Baobab Liu, Ana López-Sepulcre, Luke T. Maud, María José Maureira, Seyma Mercimek, George Moellenbrock, Shoji Mori, Hideko Nomura, Yasuhiro Oba, Ross O’Donoghue, Satoshi Ohashi, Yuki Okoda, Juan Ospina-Zamudio, Jaime Pineda, Linda Podio, Albert Rimola, Takeshi Sakai, Dominique Segura-Cox, Yancy Shirley, Brian Svoboda, Leonardo Testi, Serena Viti, Naoki Watanabe, Yoshimasa Watanabe, Yichen Zhang, and Satoshi Yamamoto

Subjects
Astrochemistry, Stellar winds, Star formation, Low mass stars, Protostars, Astrophysics, QB460-466
Abstract

We have observed the late Class I protostellar source Elias 29 at a spatial resolution of 70 au with the Atacama Large Millimeter/submillimeter Array as part of the FAUST Large Program. We focus on the line emission of SO, while that of ^34 SO, C ^18 O, CS, SiO, H ^13 CO ^+ , and DCO ^+ are used supplementarily. The spatial distribution of the SO rotational temperature ( T _rot (SO)) is evaluated by using the intensity ratio of its two rotational excitation lines. Besides in the vicinity of the protostar, two hot spots are found at a distance of 500 au from the protostar; T _rot (SO) locally rises to 53 ${}_{-15}^{+25}$ K at the interaction point of the outflow and the southern ridge, and 72 ${}_{-29}^{+66}$ K within the southeastern outflow probably due to a jet-driven bow shock. However, the SiO emission is not detected at these hot spots. It is likely that active gas accretion through the disk-like structure and onto the protostar still continues even at this evolved protostellar stage, at least sporadically, considering the outflow/jet activities and the possible infall motion previously reported. Interestingly, T _rot (SO) is as high as 20–30 K even within the quiescent part of the southern ridge apart from the protostar by 500–1000 au without clear kinematic indication of current outflow/jet interactions. Such a warm condition is also supported by the low deuterium fractionation ratio of HCO ^+ estimated by using the H ^13 CO ^+ and DCO ^+ lines. The B-type star HD147889 ∼0.5 pc away from Elias 29, previously suggested as a heating source for this region, is likely responsible for the warm condition of Elias 29.

Published
2025
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2. ALMA Observations of Massive Clouds in the Central Molecular Zone: External-pressure-confined Dense Cores and Salpeter-like Core Mass Functions

Author

Zhenying Zhang, Xing Lu, Tie Liu, Sheng-Li Qin, Adam Ginsburg, Yu Cheng, Hauyu Baobab Liu, Daniel L. Walker, Xindi Tang, Shanghuo Li, Qizhou Zhang, Thushara Pillai, Jens Kauffmann, Cara Battersby, Siyi Feng, Suinan Zhang, Qi-Lao Gu, Fengwei Xu, Wenyu Jiao, Xunchuan Liu, Li Chen, Qiu-yi Luo, Xiaofeng Mai, Zi-yang Li, Dongting Yang, Xianjin Shen, Meizhu Liu, and Zhiqiang Shen

Subjects
Galactic center, Star formation, Molecular clouds, Astrophysics, QB460-466
Abstract

We present Atacama Large Millimeter/submillimeter Array Band 6 (1.3 mm) observations of dense cores in three massive molecular clouds within the central molecular zone (CMZ) of the Milky Way, including the Dust Ridge cloud e, Sgr C, and the 20 km s ^−1 cloud, at a spatial resolution of 2000 au. Among the 834 cores identified from the 1.3 mm continuum, we constrain temperatures and linewidths of 253 cores using local thermodynamic equilibrium methods to fit the H _2 CO and/or CH _3 CN spectra. We determine their masses using the 1.3 mm dust continuum and derived temperatures, and then evaluate their virial parameters using the H _2 CO and/or CH _3 CN linewidths and construct the core mass functions (CMFs). We find that the contribution of external pressure is crucial for the virial equilibrium of the dense cores in the three clouds, which contrasts with the environment in the Galactic disk where dense cores are already bound, even without the contribution of external pressure. With our new temperature estimates we also find that the CMFs show a Salpeter-like slope in the high-mass (≳3–6 M _⊙ ) end, a change from previous works. Combined with the possible top-heavy initial mass functions (IMFs) in the CMZ, our result suggests that gas accretion and further fragmentation may play important roles in transforming the CMF to the IMF.

Published
2025
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3. CircHIPK3 relieves vascular calcification via mediating SIRT1/PGC-1α/MFN2 pathway by interacting with FUS

Author

Siyi Feng, Youfei Qi, Zhanxiang Xiao, Hao Chen, Sahua Liu, Haimei Luo, Hongfei Wu, and Wenbo Zhang

Subjects
CircHIPK3, Calcification, FUS, SIRT1/PGC-1α signaling, Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Abstract Background Circular RNAs (circRNAs) have been reported to regulate the biological processes of human diseases. CircHIPK3 has been implicated in vascular calcification, but the downstream regulatory mechanisms remain unclear. Our study aimed to understand the regulatory function of circHIPK3 in vascular calcification. Methods CircHIPK3 expression in atherosclerosis (AS) serum samples and vascular smooth muscle cells (VSMCs) calcification model was assessed by quantitative real-time polymerase chain reaction (qRT-PCR). The binding relationships between fused in sarcoma (FUS) and circHIPK3 or sirtuin 1 (SIRT1) were verified by RNA immunoprecipitation (RIP) assay and RNA pull-down assays. Alkaline phosphatase (ALP) activity and alizarin red staining assays were performed to evaluate the biological effect of β-glycerophosphate (β-GP) and circHIPK3 on calcium deposition. qRT-PCR and western blot assays were used to examine the effect of β-GP, circHIPK3, SIRT1, mitofusin 2 (MFN2), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) on VSMCs calcification and the expression of calcification-related proteins. Results In AS serum samples and VSMCs calcification model, the expression of circHIPK3 was significantly reduced. CircHIPK3 overexpression inhibited ALP activity and calcium deposition in β-GP-induced VSMCs. Moreover, circHIPK3 could recruit FUS to further stabilize SIRT1 mRNA. CircHIPK3 promoted MFN2 expression to alleviate VSMCs calcification via activating SIRT1/PGC-1α signaling. Conclusion The positive regulation of circHIPK3/FUS/SIRT1/PGC-1α/MFN2 signaling pathway contributed to the alleviate VSMCs calcification, revealing a novel regulatory axis for vascular calcification.

Published
2023
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4. Geological structure recognition model based on improved random forest algorithm

Author

Huaixiu WANG, Siyi FENG, and Zuiliang LIU

Subjects
geological structure identification, seismic attribute fusion, random forest algorithm, geological model, Mining engineering. Metallurgy, TN1-997
Abstract

Seismic attributes are often used for structural interpretation and prediction. In order to overcome the problems of multiple solutions and uncertainty caused by single seismic attribute prediction, seismic multi-attribute fusion technology is used to interpret and predict geological structures. Based on the classical machine learning random forest algorithm model, an improved random forest algorithm is proposed to fuse and classify multiple seismic attributes. Combining the seismic multi-attribute fusion technology with the improved random forest algorithm, a geological structure recognition model based on the improved random forest algorithm is established. Taking the second mining area of the second belt of Shanxi Xinyuan Coal Co., Ltd. as the research area, based on the twelve seismic attributes extracted from the three-dimensional seismic exploration results, through the attribute correlation analysis and feature importance analysis of the twelve attributes, according to the results, all twelve attributes are retained for subsequent attribute fusion. Using the exposed and verified geological structure faults and collapse columns as sample labels, an improved grid search optimization algorithm is proposed. The number of classifiers and the maximum feature number of a single decision tree are combined to search the grid. The algorithm model is established based on Python language platform. The experimental results show that the prediction accuracy of the improved algorithm model reaches 97%, After subsequent model verification, it is proved that compared with several algorithms such as logistic regression, gradient lifting and decision tree, the improved random forest algorithm can more effectively identify abnormal bodies such as faults and collapse columns in geological structures, with higher recognition accuracy and wider applicability.

Published
2023
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5. Contrast enhanced ultrasound combined with serology predicts hepatocellular carcinoma recurrence: a retrospective observation cohort study

Author

Haibin Tu, Siyi Feng, Lihong Chen, Yujie Huang, Juzhen Zhang, and Xiaoxiong Wu

Subjects
hepatocellular carcinoma, contrast-enhanced ultrasound, early recurrence, prediction, serological markers, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282
Abstract

ObjectivesTo construct a novel model based on contrast-enhanced ultrasound (CEUS) and serological biomarkers to predict the early recurrence (ER) of primary hepatocellular carcinoma within 2 years after hepatectomy.MethodsA total of 466 patients who underwent CEUS and curative resection between 2016.1.1 and 2019.1.1 were retrospectively recruited from one institution. The training and testing cohorts comprised 326 and 140 patients, respectively. Data on general characteristics, CEUS Liver Imaging Reporting and Data System (LI-RADS) parameters, and serological were collected. Univariate analysis and multivariate Cox proportional hazards regression model were used to evaluate the independent prognostic factors for tumor recurrence, and the Contrast-enhanced Ultrasound Serological (CEUSS) model was constructed. Different models were compared using prediction error and time-dependent area under the receiver operating characteristic curve (AUC). The CEUSS model's performances in ER prediction were assessed.ResultsThe baseline data of the training and testing cohorts were equal. LI-RADS category, α-fetoprotein level, tumor maximum diameter, total bilirubin level, starting time, iso-time, and enhancement pattern were independent hazards, and their hazards ratios were 1.417, 1.309, 1.133, 1.036, 0.883, 0.985, and 0.70, respectively. The AUCs of CEUSS, BCLC,TNM, and CNLC were 0.706, 0.641, 0.647, and 0.636, respectively, in the training cohort and 0.680, 0.583, 0.607, and 0.597, respectively, in the testing cohort. The prediction errors of CEUSS, BCLC, TNM, and CNLC were 0.202, 0.205, 0.205, and 0.200, respectively, in the training cohort and 0.204, 0.221, 0.219, and 0.211, respectively, in the testing cohort.ConclusionsThe CEUSS model can accurately and individually predict ER before surgery and may represent a new tool for individualized treatment.

Published
2023
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6. Caffeic Acid Phenethyl Ester Encapsulated in Self-Assemble Rice Peptides Nanoparticles: Storage Stability, In Vitro Release, and Their Interaction Mechanisms

Author

Xinyue Wang, Siyi Feng, and Hongdong Song

Subjects
rice peptides, self-assembly, CAPE, water solubility, fluorescence quenching, Chemical technology, TP1-1185
Abstract

Caffeic acid phenethyl ester (CAPE) is an important active component of propolis with many bioactivities. However, its efficiency and practical application are restricted due to its poor aqueous solubility and storage stability. In this study, a nanocarrier was fabricated to encapsulate CAPE using self-assembled rice peptides obtained by controllable enzymolysis. The physicochemical properties, encapsulation efficiency, and loading capacity of rice peptides nanoparticles (RPNs) were characterized. The storage stability, in vitro release, and interaction mechanisms between CAPE and RPNs were investigated. The results showed that RPNs, mainly assembled by disulfide bonds and hydrogen bonds, possessed an effective diameter of around 210 nm and a high encapsulation efficiency (77.77%) and loading capacity (3.89%). Importantly, the water solubility of CAPE was increased by 45 times after RPNs encapsulation. Moreover, RPNs encapsulation also significantly increased CAPE stability, about 1.4-fold higher than that of unencapsulated CAPE after 18-day storage. An in vitro release study demonstrated that RPNs could delay the release of CAPE, implying a better CAPE protection against extreme environments during digestion. Hydrogen bond and van der Waals force are the predominant interaction forces between RPNs and CAPE. Therefore, the newly developed nanoparticle is a potential delivery system that could effectively improve the aqueous solubility and stability of CAPE.

Published
2024
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7. Investigations of Massive Filaments and Star Formation (INFANT). I. Core Identification and Core Mass Function

Author

Yu Cheng, Xing Lu, Patricio Sanhueza, Hauyu Baobab Liu, Qizhou Zhang, Roberto Galván-Madrid, Ke Wang, Fumitaka Nakamura, Tie Liu, Siyi Feng, Shanghuo Li, Sihan Jiao, Kei E. I. Tanaka, Xunchuan Liu, Pak Shing Li, Qiuyi Luo, Qilao Gu, Yuxin Lin, and Andrés E. Guzmán

Subjects
Star formation, Initial mass function, Interstellar filaments, Surveys, Molecular clouds, Astrophysics, QB460-466
Abstract

Filamentary structures are ubiquitously found in high-mass star-forming clouds. To investigate the relationship between filaments and star formation, we carry out the INFANT (Investigations of Massive Filaments and Sar Formation) survey, a multiscale, multiwavelength survey of massive filamentary clouds with Atacama Large Millimeter/submillimeter Array (ALMA) band 3/band 6 and Very Large Array K band. In this first paper, we present the ALMA band 6 continuum observations toward a sample of eight high-mass star-forming filaments. We covered each target with an approximately rectangular mosaic field of view with two 12 m array configurations, achieving an angular resolution of ∼0.″6 (2700 au at 4.5 kpc) and a continuum rms of ∼0.1 mJy beam ^−1 (∼0.06 M _⊙ in gas mass assuming 15 K). We identify cores using the getsf and astrodendro and find the former is more robust in terms of both identification and measuring flux densities. We identify in total 183 dense cores (15–36 cores in each cloud) and classify their star formation states via outflow and warm gas tracers. The protostellar cores are statistically more massive than the prestellar cores, possibly indicating further accretion onto cores after the formation of protostars. For the high-mass end ( ${M}_{\mathrm{core}}$ > 1.5 M _⊙ ) of the core mass function (CMF) we derive a power-law index of −1.15 ± 0.12 for the whole sample and −1.70 ± 0.25 for the prestellar population. We also find a steepening trend in CMF with cloud evolution (−0.89 ± 0.15 for the young group versus. −1.44 ± 0.25 for the evolved group) and discuss its implications for cluster formation.

Published
2024
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8. CO Observations of Early-mid Stage Major Mergers in the MaNGA Survey

Author

Qingzheng Yu, Taotao Fang, Cong Kevin Xu, Shuai Feng, Siyi Feng, Yu Gao, Xue-Jian Jiang, and Ute Lisenfeld

Subjects
Galaxy pairs, Galaxy mergers, Molecular gas, Star formation, Astrophysics, QB460-466
Abstract

We present a study of the molecular gas in early-mid stage major mergers, with a sample of 43 major-merger galaxy pairs selected from the Mapping Nearby Galaxies at Apache Point Observatory survey and a control sample of 195 isolated galaxies selected from the xCOLD GASS survey. Adopting kinematic asymmetry as a new effective indicator to describe the merger stage, we aim to study the role of molecular gas in the merger-induced star formation enhancement along the merger sequence of galaxy pairs. We obtain the molecular gas properties from CO observations with the James Clerk Maxwell Telescope, Institut de Radioastronomie Milimetrique 30 m telescope, and the MaNGA-ARO Survey of CO Targets survey. Using these data, we investigate the differences in molecular gas fraction ( ${f}_{{{\rm{H}}}_{2}}$ ), star formation rate (SFR), star formation efficiency (SFE), molecular-to-atomic gas ratio ( ${M}_{{{\rm{H}}}_{2}}$ / M _H _i ), total gas fraction ( f _gas ), and the SFE of total gas (SFE _gas ) between the pair and control samples. In the full pair sample, our results suggest the ${f}_{{{\rm{H}}}_{2}}$ of paired galaxies is significantly enhanced, while the SFE is comparable to that of isolated galaxies. We detect significantly increased ${f}_{{{\rm{H}}}_{2}}$ and ${M}_{{{\rm{H}}}_{2}}$ / M _H _i in paired galaxies at the pericenter stage, indicating an accelerated transition from atomic gas to molecular gas due to interactions. Our results indicate that the elevation of ${f}_{{{\rm{H}}}_{2}}$ plays a major role in the enhancement of global SFR in paired galaxies at the pericenter stage, while the contribution of enhanced SFE in specific regions requires further explorations through spatially resolved observations of a larger sample spanning a wide range of merger stages.

Published
2024
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9. Parametric Dynamic Distributed Containment Control of Continuous-Time Linear Multi-Agent Systems with Specified Convergence Speed

Author

Fei Yan, Siyi Feng, Xiangbiao Liu, and Tao Feng

Subjects
continuous-time MAS, containment control, dominant poles assignment, convergence speed, Chemical technology, TP1-1185
Abstract

This paper focuses on the distributed containment control of continuous-time linear multi-agent systems (MASs) with multiple leaders over fixed topology. A parametric dynamic compensated distributed control protocol is proposed in which both the information from the observer in the virtual layer and actual adjacent agents are employed. The necessary and sufficient conditions of the distributed containment control are derived based on the standard linear quadratic regulator (LQR). On this basis, the dominant poles are configured by using the modified linear quadratic regulator (MLQR) optimal control and Geršgorin’s circle criterion, hence the containment control with specified convergence speed of the MAS is achieved. Another main advantage of the proposed design is, in the case of virtual layer failure, by adjusting parameters the dynamic control protocol reduces to static, and the convergence speed can still be specified through the dominant pole assignment method combined with inverse optimal control. Finally, typical numerical examples are presented to demonstrate the effectiveness of theoretical results.

Published
2023
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10. A High-mass, Young Star-forming Core Escaping from Its Parental Filament

Author

Zhiyuan Ren, Xi Chen, Tie Liu, Emma Mannfors, Leonardo Bronfman, Fengwei Xu, Siyi Feng, Hongli Liu, Fanyi Meng, Amelia M. Stutz, Shanghuo Li, Chang Won Lee, Ke Wang, Jianwen Zhou, Di Li, Chen Wang, Chakali Eswaraiah, Anandmayee Tej, Long-Fei Chen, and Hui Shi

Subjects
Star formation, Young stellar objects, Dense interstellar clouds, Interstellar filaments, Gravitational collapse, Astrophysics, QB460-466
Abstract

We studied the unique kinematic properties in massive filament G352.63-1.07 at 10 ^3 au spatial scale with the dense molecular tracers observed with the Atacama Large Millimeter/submillimeter Array. We find the central massive core M1 (12 M _⊙ ) being separated from the surrounding filament with a velocity difference of $v-{\overline{v}}_{\mathrm{sys}}=-2\,\mathrm{km}\,{{\rm{s}}}^{-1}$ and a transverse separation within 3″. Meanwhile, as shown in multiple dense-gas tracers, M1 has a spatial extension closely aligned with the main filament and is connected to the filament toward both its ends. M1 thus represents a very beginning state for a massive, young star-forming core escaping from the parental filament, within a timescale of ∼4000 yr. Based on its kinetic energy (3.5 × 10 ^44 erg), the core escape is unlikely solely due to the original filament motion or magnetic field but requires more energetic events such as a rapid intense anisotropic collapse. The released energy also seems to noticeably increase the environmental turbulence. This may help the filament to become stabilized again.

Published
2023
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11. Market Impact of Foot-and-Mouth Disease Control Strategies: A UK Case Study

Author

Siyi Feng, Myles Patton, and John Davis

Subjects
foot-and-mouth disease, partial equilibrium model, disease control strategy, market impact, economics, Veterinary medicine, SF600-1100
Abstract

Foot-and-mouth disease (FMD) poses a serious threat to the agricultural sector due to its highly contagious nature. Outbreaks of FMD can lead to substantial disruptions to livestock markets due to loss of production and access to international markets. In a previously FMD-free country, the use of vaccination to augment control of an FMD outbreak is increasingly being recognized as an alternative control strategy to direct slaughtering [stamping-out (SO)]. The choice of control strategy has implications on production, trade, and hence prices of the sector. Specific choice of eradication strategies depends on their costs and benefits. Economic impact assessments are often based on benefit–cost framework, which provide detailed information on the changes in profit for a farm or budget implications for a government (1). However, this framework cannot capture price effects caused by changes in production due to culling of animals; access to international markets; and consumers’ reaction. These three impacts combine to affect equilibrium within commodity markets (2). This paper provides assessment of sectoral level impacts of the eradication choices of FMD outbreaks, which are typically not available from benefit–cost framework, in the context of the UK. The FAPRI-UK model, a partial equilibrium model of the agricultural sector, is utilized to investigate market outcomes of different control strategies (namely SO and vaccinate-to-die) in the case of FMD outbreaks. The outputs from the simulations of the EXODIS epidemiological model (number of animals culled/vaccinated and duration of outbreak) are used as inputs within the economic model to capture the overall price impact of the animal destruction, export ban, and consumers’ response.

Published
2017
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13. ALMA–IRDC: dense gas mass distribution from cloud to core scales

Author

Jonathan C. Tan, I. Jimenez-Serra, Richard J. Parker, Ashley T. Barnes, Álvaro Sánchez-Monge, Adam Avison, L. Moser, Francesco Fontani, K. Wang, Frank Bigiel, Steven N. Longmore, Jonathan D. Henshaw, Jaime E. Pineda, Chi Yan Law, Giuliana Cosentino, Paola Caselli, Shuo Kong, Siyi Feng, Avison, A. [0000-0002-2562-8609], European Research Council (ERC), Agencia Estatal de Investigación (AEI), Deutsche Forschungsgemeinschaft (DFG), East Asia Core Observatories Association (EACOA), National Natural Science Foundation of China (NSFC), National Key Research and Development Program of China, and Peking University

Subjects
Milky Way, Continuum (design consultancy), FOS: Physical sciences, Astrophysics, 01 natural sciences, Virial theorem, Spectral line, massive [stars], 0103 physical sciences, Cluster (physics), 010303 astronomy & astrophysics, QC, Solar and Stellar Astrophysics (astro-ph.SR), QB, Physics, formation [stars], Mass distribution, 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics, Orders of magnitude (time), 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), clouds [ISM]
Abstract

Infrared dark clouds (IRDCs) are potential hosts of the elusive early phases of high-mass star formation (HMSF). Here we conduct an in-depth analysis of the fragmentation properties of a sample of 10 IRDCs, which have been highlighted as some of the best candidates to study HMSF within the Milky Way. To do so, we have obtained a set of large mosaics covering these IRDCs with ALMA at band 3 (or 3mm). These observations have a high angular resolution (~3arcsec or ~0.05pc), and high continuum and spectral line sensitivity (~0.15mJy/beam and ~0.2K per 0.1km/s channel at the N2H+(1-0) transition). From the dust continuum emission, we identify 96 cores ranging from low- to high-mass (M = 3.4 to 50.9Msun) that are gravitationally bound (alpha_vir = 0.3 to 1.3) and which would require magnetic field strengths of B = 0.3 to 1.0mG to be in virial equilibrium. We combine these results with a homogenised catalogue of literature cores to recover the hierarchical structure within these clouds over four orders of magnitude in spatial scale (0.01pc to 10pc). Using supplementary observations at an even higher angular resolution, we find that the smallest fragments (16Msun without further fragmentation. These high-mass cores contain trans-sonic non-thermal motions, are kinematically sub-virial, and require moderate magnetic field strengths for support against collapse. The identification of these potential sites of high-mass star formation represents a key step in allowing us to test the predictions from high-mass star and cluster formation theories., 21(+6 in appendix) pages, 12(+3) figures, 3(+3) tables. Machine-readable versions of Table A1, A2 and A3 are available online. Accepted for publication in MNRAS

Published
2021
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14. The ALMA Survey of 70 {\mu}m Dark High-mass Clumps in Early Stages (ASHES). VI. The core-scale CO-depletion

Author

Giovanni Sabatini, Stefano Bovino, Patricio Sanhueza, Kaho Morii, Shanghuo Li, Elena Redaelli, Qizhou Zhang, Xing Lu, Siyi Feng, Daniel Tafoya, Natsuko Izumi, Takeshi Sakai, Ken’ichi Tatematsu, and David Allingham

Subjects
Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Studying the physical and chemical properties of cold and dense molecular clouds is crucial for the understanding of how stars form. Under the typical conditions of infrared dark clouds, CO is removed from the gas phase and trapped on to the surface of dust grains by the so-called depletion process. This suggests that the CO depletion factor ($f_{\rm D}$) can be a useful chemical indicator for identifying cold and dense regions (i.e., prestellar cores). We have used the 1.3 mm continuum and C$^{18}$O(2-1) data observed at the resolution of $\sim$5000 au in the ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES) to construct averaged maps of $f_{\rm D}$ in twelve clumps to characterise the earliest stages of the high-mass star formation process. The average $f_{\rm D}$ determined for 277 of the 294 ASHES cores follows an unexpected increase from the prestellar to the protostellar stage. If we exclude the temperature effect due to the slight variations in the NH$_3$ kinetic temperature among different cores, we explain this result as a dependence primarily on the average gas density, which increases in cores where protostellar conditions prevail. This shows that $f_{\rm D}$ determined in high-mass star-forming regions at the core scale is insufficient to distinguish among prestellar and protostellar conditions for the individual cores, and should be complemented by information provided by additional tracers. However, we confirm that the clump-averaged $f_{\rm D}$ values correlates with the luminosity-to-mass ratio of each source, which is known to trace the evolution of the star formation process., Comment: 20 pages, 10 figures, 2 tables. Accepted for publication in The Astrophysical Journal (ApJ)

Published
2022

15. Contrast enhanced ultrasound predict hepatocellular carcinoma recurrence: a retrospective observation cohort study

Author

Haibin Tu, Siyi Feng, Lihong Chen, Yujie Huang, Juzhen Zhang, Lingxuan Zhu, and Xiaoxiong Wu

Abstract

Background: Surgery is the main treatment for hepatocellular carcinoma (HCC), but early recurrence (ER) affects patients' prognosis. Non-invasive screening of high-risk recurrence groups is important for precise treatment to formulate personalized treatment. contrast-enhanced ultrasound (CEUS) may realize this scenarioObjectives: Construction and validation of a non-invasive prediction model for ER of HCC after surgery based on CEUS and serological biomarkers.Methods: 466 patients who underwent CEUS and curative resection between 2016.1.1 and 2019.1.1 were retrospectively recruited from one institution. The training and testing cohorts comprised 326 and 140 patients. We collected CEUS Liver Imaging Reporting and Data System (LI-RADS) grading and serological indicators. Finding risk factors for recurrence of HCC after surgery using univariate and multvariatel analysis, and the Contrast-enhanced Ultrasound Serological (CEUSS) model was constructed. Different models were compared using time-dependent area under the receiver operating characteristic curve (td-AUC) and prediction error. The CEUSS model’s performances in ER prediction were assessed.Results: Base-line data of the training and testing cohorts were equal. LI-RADS category, α-fetoprotein level, tumor maximum diameter, total bilirubin level, starting time, iso-time, and enhancement pattern were independent hazards, and their hazards ratios were 1.417, 1.309, 1.133, 1.036, 0.883, 0.985, and 0.70, respectively. The AUCs of CEUSS, BCLC, TNM, and CNLC were 0.706, 0.641, 0.647, and 0.636, respectively, in the training cohort and 0.680, 0.583, 0.607, and 0.597, respectively, in the testing cohort. The prediction errors of CEUSS, BCLC, TNM, and CNLC were 0.202, 0.205, 0.205, and 0.200, respectively, in the training cohort and 0.204, 0.221, 0.219, and 0.211, respectively, in the testing cohort.Conclusions: CEUSS model can effectively screen out high-risk recurrence population, providing an important basis for precise treatment.

Published
2022
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16. Chemical and Physical Characterization of the Isolated Protostellar Source CB68: FAUST IV

Author

Muneaki Imai, Yoko Oya, Brian Svoboda, Hauyu Baobab Liu, Bertrand Lefloch, Serena Viti, Yichen Zhang, Cecilia Ceccarelli, Claudio Codella, Claire J. Chandler, Nami Sakai, Yuri Aikawa, Felipe O. Alves, Nadia Balucani, Eleonora Bianchi, Mathilde Bouvier, Gemma Busquet, Paola Caselli, Emmanuel Caux, Steven Charnley, Spandan Choudhury, Nicolas Cuello, Marta De Simone, Francois Dulieu, Aurora Durán, Lucy Evans, Cécile Favre, Davide Fedele, Siyi Feng, Francesco Fontani, Logan Francis, Tetsuya Hama, Tomoyuki Hanawa, Eric Herbst, Shingo Hirano, Tomoya Hirota, Andrea Isella, Izaskun Jímenez-Serra, Doug Johnstone, Claudine Kahane, Romane Le Gal, Laurent Loinard, Ana López-Sepulcre, Luke T. Maud, María José Maureira, Francois Menard, Seyma Mercimek, Anna Miotello, George Moellenbrock, Shoji Mori, Nadia M. Murillo, Riouhei Nakatani, Hideko Nomura, Yasuhiro Oba, Ross O’Donoghue, Satoshi Ohashi, Yuki Okoda, Juan Ospina-Zamudio, Jaime Pineda, Linda Podio, Albert Rimola, Takeshi Sakai, Dominique Segura-Cox, Yancy Shirley, Vianney Taquet, Leonardo Testi, Charlotte Vastel, Naoki Watanabe, Yoshimasa Watanabe, Arezu Witzel, Ci Xue, Bo Zhao, Satoshi Yamamoto, Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Academia Sinica, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Department of Astronomy [Tokyo], The University of Tokyo (UTokyo), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Università degli Studi di Perugia = University of Perugia (UNIPG), Max-Planck-Institut für Extraterrestrische Physik (MPE), Centre National d'Études Spatiales [Toulouse] (CNES), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Japan Science and Technology Agency, European Research Council, European Commission, Agencia Estatal de Investigación (España), National Science Foundation (US), Ministerio de Ciencia, Innovación y Universidades (España), and Ministry of Education, Culture, Sports, Science and Technology (Japan)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Star Formation, Circumstellar Disks, Interstellar Molecules, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Imai et al., The chemical diversity of low-mass protostellar sources has so far been recognized, and environmental effects are invoked as its origin. In this context, observations of isolated protostellar sources without the influence of nearby objects are of particular importance. Here, we report the chemical and physical structures of the low-mass Class 0 protostellar source IRAS 16544−1604 in the Bok globule CB 68, based on 1.3 mm Atacama Large Millimeter/submillimeter Array observations at a spatial resolution of ∼70 au that were conducted as part of the large program FAUST. Three interstellar saturated complex organic molecules (iCOMs), CH3OH, HCOOCH3, and CH3OCH3, are detected toward the protostar. The rotation temperature and the emitting region size for CH3OH are derived to be 131 ± 11 K and ∼10 au, respectively. The detection of iCOMs in close proximity to the protostar indicates that CB 68 harbors a hot corino. The kinematic structure of the C18O, CH3OH, and OCS lines is explained by an infalling–rotating envelope model, and the protostellar mass and the radius of the centrifugal barrier are estimated to be 0.08–0.30 M⊙ and, This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.01376.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The authors acknowledge financial support from JSPS and MAEE under the Japan–France Integrated Action Program (SAKURA: 25765VC). D.J. is supported by NRC Canada and by an NSERC Discovery Grant. E.B. and G.B. acknowledge funding from the European Research Council under the European Union's Horizon 2020 research and innovation program, for the project "The Dawn of Organic Chemistry," grant agreement No. 741002. G.B. acknowledges support from the PID2020-117710GB-I00 grant funded by MCIN/AEI/10.13039/501100011033 and from the Unit of Excellence María de Maeztu 2020–2023 award to the Institute of Cosmos Sciences (CEX2019-00918-M). I.J.-S. has received partial support from the Spanish State Research Agency (AEI) through project Nos. PID2019-105552RB-C41 and MDM-2017-0737 Unidad de Excelencia "Maria de Maeztu" - Centro de Astrobiologia (CSIC-INTA). This study is supported by grants-in-aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (18H05222, 18J11010, 19H05069, 19K14753, and 21K13954).

Published
2022
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17. Erratum: 'The ALMA Survey of 70micron dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477' (2021, ApJ, 923, 147)

Author

Kaho Morii, Patricio Sanhueza, Fumitaka Nakamura, James M. Jackson, Shanghuo Li, Henrik Beuther, Qizhou Zhang, Siyi Feng, Daniel Tafoya, Andrés E. Guzmán, Natsuko Izumi, Takeshi Sakai, Xing Lu, Ken’ichi Tatematsu, Satoshi Ohashi, Andrea Silva, Fernando A. Olguin, and Yanett Contreras

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

This is a correction for 2021 ApJ 923 147DOI 10.3847/1538-4357/ac2365

Published
2022

18. ALMA Observations of Massive Clouds in the Central Molecular Zone: Ubiquitous Protostellar Outflows

Author

Qizhou Zhang, Jens Kauffmann, Adam Ginsburg, Thushara Pillai, Xing Lu, Siyi Feng, Shu-ichiro Inutsuka, Steven N. Longmore, Elisabeth A. C. Mills, Cara Battersby, J. M. Diederik Kruijssen, Yu Cheng, Daniel Walker, and Shanghuo Li

Subjects
Physics, Astrochemistry, 010504 meteorology & atmospheric sciences, Star formation, Molecular cloud, Galactic Center, Continuum (design consultancy), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Spectral line, Galaxy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Outflow, 010303 astronomy & astrophysics, QC, QB, 0105 earth and related environmental sciences
Abstract

We observe 1.3~mm spectral lines at 2000~AU resolution toward four massive molecular clouds in the Central Molecular Zone of the Galaxy to investigate their star formation activities. We focus on several potential shock tracers that are usually abundant in protostellar outflows, including SiO, SO, CH$_3$OH, H$_2$CO, HC$_3$N, and HNCO. We identify 43 protostellar outflows, including 37 highly likely ones and 6 candidates. The outflows are found toward both known high-mass star forming cores and less massive, seemingly quiescent cores, while 791 out of the 834 cores identified based on the continuum do not have detected outflows. The outflow masses range from less than 1~$M_\odot$ to a few tens of $M_\odot$, with typical uncertainties of a factor of 70. We do not find evidence of disagreement between relative molecular abundances in these outflows and in nearby analogs such as the well-studied L1157 and NGC7538S outflows. The results suggest that i) protostellar accretion disks driving outflows ubiquitously exist in the CMZ environment, ii) the large fraction of candidate starless cores is expected if these clouds are at very early evolutionary phases, with a caveat on the potential incompleteness of the outflows, iii) high-mass and low-mass star formation is ongoing simultaneously in these clouds, and iv) current data do not show evidence of difference between the shock chemistry in the outflows that determines the molecular abundances in the CMZ environment and in nearby clouds., 43 pages, 25 figures, 3 tables, accepted for publication in ApJ

Published
2021

19. FAUST II. Discovery of a Secondary Outflow in IRAS 15398-3359: Variability in Outflow Direction during the Earliest Stage of Star Formation?

Author

Cécile Favre, Serena Viti, Luke T. Maud, Davide Fedele, S. Mercimek, Anna Miotello, Naoki Watanabe, Spandan Choudhury, Siyi Feng, Charlotte Vastel, Ross O'Donoghue, Brian Svoboda, Ci Xue, Claudine Kahane, Yuki Okoda, Doug Johnstone, Yoshimasa Watanabe, Andrea Isella, C. Codella, Yoko Oya, Linda Podio, Nami Sakai, J. Ospina-Zamudio, G. A. Moellenbrock, Aurora Durán, Yancy L. Shirley, Jaime E. Pineda, Paola Caselli, Yasuhiro Oba, François Dulieu, Laurent Loinard, Leonardo Testi, Muneaki Imai, Takeshi Sakai, Arezu Witzel, María José Maureira, Tomoyuki Hanawa, Francesco Fontani, Izaskun Jiménez-Serra, Lucy Evans, Marta De Simone, Felipe O. Alves, Logan Francis, Vianney Taquet, Dominique Segura-Cox, Emmanuel Caux, Mathilde Bouvier, Riouhei Nakatani, Bertrand Lefloch, Yichen Zhang, Nadia Balucani, Cecilia Ceccarelli, Tetsuya Hama, Satoshi Yamamoto, H. Nomura, Claire J. Chandler, Albert Rimola, Bo Zhao, Shoji Mori, Shu-ichiro Inutsuka, Tomoya Hirota, Satoshi Ohashi, Nadia M. Murillo, Eric Herbst, Steven B. Charnley, E. Bianchi, Ana López-Sepulcre, Yuri Aikawa, Francois Menard, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Okoda, Y. [0000-0003-3655-5270], Oya, Y. [0000-0002-0197-8751], Francis, L. [0000-0001-8822-6327], Johnstone, D. [0000-0002-6773-459X], Inutsuka, S. I. [0000-0003-4366-6518], Ceccarelli, C. [0000-0001-9664-6292], Codella, C. [0000-0003-1514-3074], Chandler, C. [0000-0002-7570-5596], Sakai, N. [0000-0002-3297-4497], Aikawa, Y. [0000-0003-3283-6884], Alves, F. [0000-0002-7945-064X], Balucani, N. [0000-0001-5121-5683], Bianchi, E. [0000-0001-9249-7082], Bouvier, M. [0000-0003-0167-0746], Caselli, P. [0000-0003-1481-7911], De Simone, M. [0000-0001-5659-0140], Feng, S. [0000-0002-4707-8409], Fontani, F. [0000-0003-0348-3418], Hama, T. [0000-0002-4991-4044], Hanawa, T. [0000-0002-7538-581X], Herbst, E. [0000-0002-4649-2536], Hirota, T. [0000-0003-1659-095X], Imai, M. [0000-0002-5342-6262], Isella, A. [0000-0001-8061-2207], Jiménez Serra, I. [0000-0003-4493-8714], Kahane, C. [0000-0003-1691-4686], Loinard, L. [0000-0002-5635-3345], López Sepulcre, A. [0000-0002-6729-3640], Maud, L. T. [0000-0002-7675-3565], Maureira, M. J. [0000-0002-7026-8163], Menard, F. [0000-0002-1637-7393], Miotello, A. [0000-0002-7997-2528], Moellenbrock, G. [0000-0002-3296-8134], Oba, Y. [0000-0002-6852-3604], Ohashi, S. [0000-0002-9661-7958], Pineda, J. E. [0000-0002-3972-1978], Rimola, A. [0000-0002-9637-4554], Sakai, T. [0000-0003-4521-7492], Segura Cox, D. [0000-0003-3172-6763], Svoboda, B. [0000-0002-8502-6431], Taquet, V. [0000-0003-0407-7489], European Research Council (ERC), Agencia Estatal de Investigación (AEI), and Japan Society for the Promotion of Science (JSPS)

Subjects
Astrochemistry, FOS: Physical sciences, Astrophysics, 01 natural sciences, 7. Clean energy, Submillimeter Array, Stellar jets, Interstellar medium, 0103 physical sciences, Protostar, 010303 astronomy & astrophysics, Shocks, Solar and Stellar Astrophysics (astro-ph.SR), Line (formation), Astrochimica, Physics, [PHYS]Physics [physics], Accretion (meteorology), 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Interstellar molecules, Astrophysics - Astrophysics of Galaxies, Young stellar objects, Protostars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Outflow, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We have observed the very low-mass Class 0 protostar IRAS 15398−3359 at scales ranging from 50 to 1800 au, as part of the Atacama Large Millimeter/Submillimeter Array Large Program FAUST. We uncover a linear feature, visible in H2CO, SO, and C18O line emission, which extends from the source in a direction almost perpendicular to the known active outflow. Molecular line emission from H2CO, SO, SiO, and CH3OH further reveals an arc-like structure connected to the outer end of the linear feature and separated from the protostar, IRAS 15398−3359, by 1200 au. The arc-like structure is blueshifted with respect to the systemic velocity. A velocity gradient of 1.2 km s−1 over 1200 au along the linear feature seen in the H2CO emission connects the protostar and the arc-like structure kinematically. SO, SiO, and CH3OH are known to trace shocks, and we interpret the arc-like structure as a relic shock region produced by an outflow previously launched by IRAS 15398−3359. The velocity gradient along the linear structure can be explained as relic outflow motion. The origins of the newly observed arc-like structure and extended linear feature are discussed in relation to turbulent motions within the protostellar core and episodic accretion events during the earliest stage of protostellar evolution. The authors thank the anonymous reviewer for invaluable comments. They are also grateful to Hauyu Baobab Liu for useful discussions. This paper makes use of the following ALMA data set: ADS/JAO.ALMA#2018.1.01205.L (PI: Satoshi Yamamoto). ALMA is a partnership of the ESO (representing its member states), the NSF (USA) and NINS (Japan), together with the NRC (Canada) and the NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the ESO, the AUI/NRAO, and the NAOJ. The authors thank to the ALMA staff for their excellent support. This work is supported by the projects PRIN-INAF-MAIN-STREAM 2017 Protoplanetary disks seen through the eyes of new-generation instruments, ARIEL and the astrochemical link between circumstellar disks and planets, and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programmes: The Dawn of Organic Chemistry (DOC), grant agreement No. 741002, and Astro-Chemistry Origins (ACO), grant No. 811312. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. I.J.-S. has received partial support from the Spanish FEDER (project number ESP2017-86582-C4-1-R) and the State Research Agency (AEI; project number PID2019-105552RB-C41). D.J. is supported by NRC Canada and by an NSERC Discovery Grant. This project is also supported by a Grant-in-Aid from Japan Society for the Promotion of Science (KAKENHI: Nos. 18H05222, 19H05069, 19K14753). Yuki Okoda thanks the Advanced Leading Graduate Course for Photon Science (ALPS) and Japan Society for the Promotion of Science (JSPS) for financial support. Peerreview

Published
2021
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20. Fragmentation and kinematics in high-mass star formation. CORE-extension targeting two very young high-mass star-forming regions

Author

Th. Henning, M. T. Beltrán, Stuart Lumsden, Rolf Kuiper, T. Moeller, J. Syed, Javier Ballesteros-Paredes, Siyi Feng, Ralph E. Pudritz, Riccardo Cesaroni, James Urquhart, L. Moscadelli, Thomas Peters, Sümeyye Suri, Álvaro Sánchez-Monge, Juan D. Soler, A. Ahmadi, P. D. Klaassen, Friedrich Wyrowski, Peter Schilke, Steven N. Longmore, J. M. Winters, Henrik Beuther, C. Gieser, H. Linz, D. A. Semenov, and Aina Palau

Subjects
Stars: formation, Astrophysics - astrophysics of galaxies, Continuum (design consultancy), FOS: Physical sciences, Context (language use), Astrophysics, Kinematics, Star (graph theory), 01 natural sciences, ISM: clouds, Spectral line, Stars: protostars, 0103 physical sciences, Stars: massive, 010303 astronomy & astrophysics, QC, Astrophysics::Galaxy Astrophysics, QB, Physics, ISM: kinematics and dynamics, 010308 nuclear & particles physics, Velocity gradient, Star formation, Fragmentation (computing), Astronomy and Astrophysics, Physik (inkl. Astronomie), 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA)
Abstract

Context: The formation of high-mass star-forming regions from their parental gas cloud and the subsequent fragmentation processes lie at the heart of star formation research. Aims: We aim to study the dynamical and fragmentation properties at very early evolutionary stages of high-mass star formation. Methods: Employing the NOrthern Extended Millimeter Array (NOEMA) and the IRAM 30m telescope, we observed two young high-mass star-forming regions, ISOSS22478 and ISOSS23053, in the 1.3mm continuum and spectral line emission at a high angular resolution (~0.8''). Results: We resolved 29 cores that are mostly located along filament-like structures. Depending on the temperature assumption, these cores follow a mass-size relation of approximately M~r^2.0, corresponding to constant mean column densities. However, with different temperature assumptions, a steeper mass-size relation up to M~r^3.0, which would be more likely to correspond to constant mean volume densities, cannot be ruled out. The correlation of the core masses with their nearest neighbor separations is consistent with thermal Jeans fragmentation. We found hardly any core separations at the spatial resolution limit, indicating that the data resolve the large-scale fragmentation well. Although the kinematics of the two regions appear very different at first sight - multiple velocity components along filaments in ISOSS22478 versus a steep velocity gradient of more than 50km/s/pc in ISOSS23053 - the findings can be explained within the framework of a dynamical cloud collapse scenario. Conclusions: While our data are consistent with a dynamical cloud collapse scenario and subsequent thermal Jeans fragmentation, the importance of additional environmental properties, such as the magnetization of the gas or external shocks triggering converging gas flows, is nonetheless not as well constrained and would require future investigation., Comment: 16 pages, 16 figures, accepted for Astronomy and Astrophysics, a higher-resolution version can also be found at https://www.mpia.de/homes/beuther/papers.html

Published
2021

21. The ALMA survey of 70 μm dark high-mass clumps in early stages (ASHES)

Author

Kaho Morii, Patricio Sanhueza, Fumitaka Nakamura, James M. Jackson, Shanghuo Li, Henrik Beuther, Qizhou Zhang, Siyi Feng, Daniel Tafoya, Andrés E. Guzmán, Natsuko Izumi, Takeshi Sakai, Xing Lu, Ken’ichi Tatematsu, Satoshi Ohashi, Andrea Silva, Fernando A. Olguin, and Yanett Contreras

Subjects
010308 nuclear & particles physics, Astrophysics - astrophysics of galaxies, FOS: Physical sciences, Astronomy and Astrophysics, 01 natural sciences, 7. Clean energy, Astrophysics - solar and stellar astrophysics, 787, 1569, 1565, 732, 844, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

With a mass of $\sim$1000 $M_\odot$ and a surface density of $\sim$0.5 g cm$^{-2}$, G023.477+0.114 also known as IRDC 18310-4 is an infrared dark cloud (IRDC) that has the potential to form high-mass stars and has been recognized as a promising prestellar clump candidate. To characterize the early stages of high-mass star formation, we have observed G023.477+0.114 as part of the ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). We have conducted $\sim$1."2 resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm in dust continuum and molecular line emission. We identified 11 cores, whose masses range from 1.1 $M_\odot$ to 19.0 $M_\odot$. Ignoring magnetic fields, the virial parameters of the cores are below unity, implying that the cores are gravitationally bound. However, when magnetic fields are included, the prestellar cores are close to virial equilibrium, while the protostellar cores remain sub-virialized. Star formation activity has already started in this clump. Four collimated outflows are detected in CO and SiO. H$_2$CO and CH$_3$OH emission coincide with the high-velocity components seen in the CO and SiO emission. The outflows are randomly oriented for the natal filament and the magnetic field. The position-velocity diagrams suggest that episodic mass ejection has already begun even in this very early phase of protostellar formation. The masses of the identified cores are comparable to the expected maximum stellar mass that this IRDC could form (8-19 $M_\odot$). We explore two possibilities on how IRDC G023.477+0.114 could eventually form high-mass stars in the context of theoretical scenarios., Comment: Accepted for publication in ApJ (September 1, 2021). 33 pages, 20 figures, and 5 tables

Published
2021

22. Physical and chemical structure of high-mass star-forming regions. Unraveling chemical complexity with CORE: the NOEMA large program

Author

Friedrich Wyrowski, Timea Csengeri, Th. Henning, H. Linz, S. Leurini, Pamela Klaassen, S. N. Longmore, Roberto Galván-Madrid, S. Suri, Siyi Feng, James Urquhart, Ralph E. Pudritz, Peter Schilke, C. Gieser, Vincent Piétu, J. M. Winters, D. Semenov, A. Ahmadi, Gary A. Fuller, Luke T. Maud, Thomas Peters, Stuart Lumsden, V. de Souza Magalhães, Álvaro Sánchez-Monge, Henrik Beuther, Qizhou Zhang, M. T. Beltrán, Rolf Kuiper, Aina Palau, Karl M. Menten, Luca Moscadelli, T. Möller, and Jérôme Pety

Subjects
Physics, Astrochemistry, 010504 meteorology & atmospheric sciences, Star formation, Stars: formation, Astrophysics - astrophysics of galaxies, Core sample, Astronomy and Astrophysics, Astrophysics, Physik (inkl. Astronomie), 01 natural sciences, Spectral line, ISM: molecules, Astrophysics - solar and stellar astrophysics, Stars, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Emission spectrum, Continuum (set theory), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Line (formation)
Abstract

Aims. Current star formation research centers the characterization of the physical and chemical properties of massive stars, which are in the process of formation, at the spatial resolution of individual high-mass cores. Methods. We use sub-arcsecond resolution (~0.′′4) observations with the NOrthern Extended Millimeter Array at 1.37 mm to study the dust emission and molecular gas of 18 high-mass star-forming regions. With distances in the range of 0.7−5.5 kpc, this corresponds to spatial scales down to 300−2300 au that are resolved by our observations. We combined the derived physical and chemical properties of individual cores in these regions to estimate their ages. The temperature structures of these regions are determined by fitting the H2CO and CH3CN line emission. The density profiles are inferred from the 1.37 mm continuum visibilities. The column densities of 11 different species are determined by fitting the emission lines with XCLASS. Results. Within the 18 observed regions, we identified 22 individual cores with associated 1.37 mm continuum emission and with a radially decreasing temperature profile. We find an average temperature power-law index of q = 0.4 ± 0.1 and an average density power-law index of p = 2.0 ± 0.2 on scales that are on the order of several 1000 au. Comparing these results with values of p derived from the literature presumes that the density profiles remain unchanged from clump to core scales. The column densities relative to N(C18O) between pairs of dense gas tracers show tight correlations. We applied the physical-chemical model MUlti Stage ChemicaL codE to the derived column densities of each core and find a mean chemical age of ~60 000 yr and an age spread of 20 000−100 000 yr. With this paper, we release all data products of the CORE project. Conclusions. The CORE sample reveals well-constrained density and temperature power-law distributions. Furthermore, we characterized a large variety in molecular richness that can be explained by an age spread that is then confirmed by our physical-chemical modeling. The hot molecular cores show the greatest number of emission lines, but we also find evolved cores at an evolutionary stage in which most molecules are destroyed and, thus, the spectra appear line-poor once again.

Published
2021

24. FAUST I. The hot corino at the heart of the prototypical Class I protostar L1551 IRS5

Author

Nadia Balucani, Tetsuya Hama, Bo Zhao, C. Favre, Yancy L. Shirley, Brian Svoboda, H. Nomura, Francois Menard, Yasuhiro Oba, G. Moellenbrock, Laurent Loinard, Charlotte Vastel, M. Bouvier, Shoji Mori, Andrea Isella, François Dulieu, Leonardo Testi, S. Yamamoto, E. Bianchi, Spandan Choudhury, Nami Sakai, M. De Simone, Aurora Durán, Linda Podio, Luke T. Maud, S. Mercimek, Jaime E. Pineda, D. Johnstone, Y. Oya, D. Segura Cox, P. Caselli, Ana López-Sepulcre, Claudine Kahane, Y. Aikawa, Bertrand Lefloch, M. J. Maureira, L. Evans, C. Codella, I. Jimenez-Serra, M. Imai, Naoki Watanabe, Francesco Fontani, S. Ohashi, Siyi Feng, Felipe O. Alves, Anna Miotello, Claire J. Chandler, Logan Francis, Ci Xue, Emmanuel Caux, Andrea Lusvarghi Witzel, Eric Herbst, Albert Rimola, Vianney Taquet, Steven B. Charnley, Cecilia Ceccarelli, Yoshimasa Watanabe, Y. Zhang, Davide Fedele, R. Nakatani, J. Ospina-Zamudio, Y. Okoda, Tomoya Hirota, Takeshi Sakai, S. Viti, Tomoyuki Hanawa, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Balucani, N. [0000-0001-5121-5683], De Oliveira Alves, F. [0000-0002-7945-064X], Hama, T. [0000-0002-4991-4044], Ohashi, S. [0000-0002-9661-7958], Johnstone, D. [0000-0002-6773-459X], Watanabe, Y. [0000-0002-9668-3592], Ceccarelli, C. [0000-0001-9664-6292], Pineda, J. [0000-0002-3972-1978], Fedele, D. [0000-0001-6156-0034], Mercimek, S. [0000-0002-0742-7934], Xue, C. [0000-0003-2760-2119], Sakai, N. [0000-0002-3297-4497], European Research Council (ERC), Japan Society for the Promotion of Science (KAKENHI), Agencia Estatal de Investigación (AEI), Universidad Nacional Autónoma de México (UNAM), Agence Nationale de la Recherche (ANR), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Department of Materials Science and Engineering, Shibaura Institute of Technology, Japan Society for the Promotion of Science (KAKENHI), 18H05222 19H05069 19K14753, Ministerio de Economía y Competitividad (MINECO), Universidad Nacional Autónoma de México (UNAM) IN112417 IN112820, and French National Research Agency (ANR), ANR-16-CE31-0013 ANR-15-IDEX-02

Subjects
Astrochemistry, 010504 meteorology & atmospheric sciences, Methyl formate, FOS: Physical sciences, Astrophysics, 01 natural sciences, chemistry.chemical_compound, Planet, Phase (matter), 0103 physical sciences, Protostar, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), formation [Stars], molecules [ISM], 0105 earth and related environmental sciences, Physics, Astrochimica, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, Radius, Planetary system, Astrophysics - Astrophysics of Galaxies, chemistry, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Methanol, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract

Bianchi, E. et al., The study of hot corinos in solar-like protostars has been so far mostly limited to the Class 0 phase, hampering our understanding of their origin and evolution. In addition, recent evidence suggests that planet formation starts already during Class I phase, which therefore represents a crucial step in the future planetary system chemical composition. Hence, the study of hot corinos in Class I protostars has become of paramount importance. Here, we report the discovery of a hot corino towards the prototypical Class I protostar L1551 IRS5, obtained within the ALMA (Atacama Large Millimeter/submillimeter Array) Large Program FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar-like protostars).We detected several lines from methanol and its isotopologues (13CH3OH and CH2DOH), methyl formate, and ethanol. Lines are bright towards the north component of the IRS5 binary system, and a possible second hot corino may be associated with the south component. The methanol lines' non-LTE analysis constrains the gas temperature (100 K), density (1.5 × 108 cm3), and emitting size (10 au in radius). All CH3OH and 13CH3OH lines are optically thick, preventing a reliable measure of the deuteration. The methyl formate and ethanol relative abundances are compatible with those measured in Class 0 hot corinos. Thus, based on this work, little chemical evolution from Class 0 to I hot corinos occurs., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Published
2020
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25. Seeds of Life in Space SOLIS. IX. Chemical segregation of $\rm SO_2$ and SO toward the low-mass protostellar shocked region of L1157

Author

Rafael Bachiller, Bertrand Lefloch, Serena Viti, Hauyu Baobab Liu, Linda Podio, Francesco Fontani, Siyi Feng, Cecilia Ceccarelli, P. Caselli, R. Neri, C. Codella, Ana López-Sepulcre, Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Academia Sinica, Observatorio Astronomico Nacional, Madrid, and University College of London [London] (UCL)

Subjects
Physics, 010308 nuclear & particles physics, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Stars: formation, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Space (mathematics), 01 natural sciences, Astrophysics - Astrophysics of Galaxies, ISM: lines and bands, Interstellar medium, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Stars: low-mass, Low Mass, Submillimeter: ISM, 010303 astronomy & astrophysics
Abstract

We present observations of SO and $\rm SO_2$ lines toward the shocked regions along the L1157 chemically rich outflow, taken in the context of the Seeds Of Life In Space IRAM-NOrthern Extended Millimeter Array Large Program, and supported by data from Submillimeter Array and IRAM-30 m telescope at 1.1--3.6 mm wavelengths. We simultaneously analyze, for the first time, all of the brightest shocks in the blueshifted lobe, namely, B0, B1, and B2. We found the following. (1) SO and $\rm SO_2$ may trace different gas, given that the large(-scale) velocity gradient analysis indicates for $\rm SO_2$ a volume density ($\rm 10^5\text{--}10^6\,cm^{-3}$) denser than that of the gas emitting in SO by a factor up to an order of magnitude. (2) Investigating the 0.1 pc scale field of view, we note a tentative gradient along the path of the precessing jet. More specifically, $\rm \chi({SO/SO_2})$ decreases from the B0-B1 shocks to the older B2. (3) At a linear resolution of 500--1400 au, a tentative spatial displacement between the two emitting molecules is detected, with the SO peak closer (with respect to $\rm SO_2$) to the position where the recent jet is impinging on the B1 cavity wall. Our astrochemical modeling shows that the SO and $\rm SO_2$ abundances evolve on timescales less than about 1000 years. Furthermore, the modeling requires high abundances ($2\times10^{-6}$) of both $\rm H_2S/H$ and S/H injected in the gas phase due to the shock occurrence, so pre-frozen OCS only is not enough to reproduce our new observations., Comment: 13 pages, 9 figures, accepted by ApJ on 2020 Apr. 7

Published
2020
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26. ALMA ACA and Nobeyama observations of two Orion cores in deuterated molecular lines

Author

Ke Wang, Mika Juvela, James Di Francesco, Kee-Tae Kim, Di Li, Gary A. Fuller, Mark Thompson, Quang Nguyen Luong, Xing Lu, Takeshi Sakai, Miju Kang, Patricio Sanhueza, Isabelle Ristorcelli, L. Viktor Tóth, Tie Liu, Sheng-Yuan Liu, Tomoya Hirota, Hee Weon Yi, Naomi Hirano, Neal J. Evans, Gwanjeong Kim, Satoshi Ohashi, Jeong-Eun Lee, Ryo Kandori, Minho Choi, Siyi Feng, Ken'ichi Tatematsu, Yuefang Wu, and Department of Physics

Subjects
010504 meteorology & atmospheric sciences, Continuum (design consultancy), FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, Radio telescope, Telescope, DENSE CORES, Star forming regions, law, Interstellar medium, 0103 physical sciences, Molecular clouds, Collapsing clouds, KINEMATICS, 010303 astronomy & astrophysics, TEMPERATURE, 0105 earth and related environmental sciences, Line (formation), Astrochemistry, Z-MACHINE, Physics, 45-M, Star formation, Molecular cloud, N2H+, Astronomy and Astrophysics, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, Radial velocity, DARK CLOUDS, Space and Planetary Science, GAS, Astrophysics of Galaxies (astro-ph.GA), CLOUD CORES, SUBMILLIMETER, Giant molecular clouds
Abstract

We mapped two molecular cloud cores in the Orion A cloud with the ALMA ACA 7-m Array and with the Nobeyama 45-m radio telescope. These cores have bright N$_2$D$^+$ emission in single-pointing observations with the Nobeyama 45-m radio telescope, have relatively high deuterium fraction, and are thought to be close to the onset of star formation. One is a star-forming core, and the other is starless. These cores are located along filaments observed in N$_2$H$^+$, and show narrow linewidths of 0.41 km s$^{-1}$ and 0.45 km s$^{-1}$ in N$_2$D$^+$, respectively, with the Nobeyama 45-m telescope. Both cores were detected with the ALMA ACA 7m Array in the continuum and molecular lines at Band 6. The starless core G211 shows clumpy structure with several sub-cores, which in turn show chemical differences. Also, the sub-cores in G211 have internal motions that are almost purely thermal. The starless sub-core G211D, in particular, shows a hint of the inverse P Cygni profile, suggesting infall motion. The star-forming core G210 shows an interesting spatial feature of two N$_2$D$^+$ peaks of similar intensity and radial velocity located symmetrically with respect to the single dust continuum peak. One interpretation is that the two N$_2$D$^+$ peaks represent an edge-on pseudo-disk. The CO outflow lobes, however, are not directed perpendicular to the line connecting both N$_2$D$^+$ peaks., 31 pages, 17 figures, 9 tables, to appear in ApJ (accepted April 23, 2020)

Published
2020

27. Seeds of Life in Space (SOLIS) V. Methanol and acetaldehyde in the protostellar jet-driven shocks L1157-B0 and B1

Author

E. Bianchi, Bertrand Lefloch, Roberto Neri, Nadia Balucani, Linda Podio, Cecilia Ceccarelli, Claudio Codella, M. De Simone, Paola Caselli, Siyi Feng, Ana López-Sepulcre, Silvia Spezzano, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Università degli Studi di Perugia (UNIPG), Max-Planck-Institut für Extraterrestrische Physik (MPE), College of Automation, Harbin Engineering University (HRBEU), Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Extraterrestrial Physics (MPE), and Max-Planck-Gesellschaft

Subjects
Formamide, Mean kinetic temperature, FOS: Physical sciences, Astrophysics, Spatial distribution, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Line (formation), Physics, Jet (fluid), 010308 nuclear & particles physics, Acetaldehyde, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, 3. Good health, chemistry, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Outflow, Methanol, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract

Aim: In the past, observations of protostellar shocks have been able to set constraints on the formation route of formamide (NH2CHO), exploiting its observed spatial distribution and comparison with astrochemical model predictions. In this work, we follow the same strategy to study the case of acetaldehyde (CH3CHO). Method: To this end, we used the data obtained with the IRAM-NOEMA interferometer in the framework of the Large Program SOLIS to image the B0 and B1 shocks along the L1157 blueshifted outflow in methanol (CH3OH) and acetaldehyde line emission. Results: We imaged six CH3OH and eight CH3CHO lines which cover upper level energies up to 30 K. Both species trace the B0 molecular cavity as well as the northern B1 portion, i.e. the regions where the youngest shocks (1000 yr) occurred. The CH$_3$OH and CH$_3$CHO emission peaks towards the B1b clump, where we measured the following column densities and relative abundances: 1.3 x 10^16 cm-2 and 6.5 x 10-6 (methanol), and 7 x 10^13 cm-2 and 3.5 x 10-8 (acetaldehyde). We carried out a non-LTE LVG analysis of the observed CH3OH line: the average kinetic temperature and density of the emitting gas are Tkin = 90 K and nH2 = 4 x 10^5 cm-3, respectively. The CH3OH and CH3CHO abundance ratio towards B1b is 190, varying by less than a factor 3 throughout the whole B0-B1 structure. Conclusions: The comparison of astrochemical model predictions with the observed methanol and acetaldehyde spatial distribution does not allow to distinguish whether acetaldehyde is formed on the grain mantles or rather on the gas-phase, as its gas-phase formation, dominated by the reaction of ethyl radical (CH3CH2) with atomic oxygen, is very fast. Observations of acetaldehyde in younger shocks, e.g. 10^2 yr old, or/and of the ethyl radical, whose frequencies are not presently available, are necessary to settle the issue., A&A, in press

Published
2020
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28. Molecular Cloud Cores with High Deuterium Fraction: Nobeyama Single-Pointing Survey

Author

Minho Choi, Mika Juvela, Mark Thompson, Quang Nguyễn Lu'o'ng, Jinhua He, Satoshi Ohashi, Xing Lu, Neal J. Evans, Jungha Kim, Ryo Kandori, Isabelle Ristorcelli, O. Fehér, Hiroko Shinnaga, Gary A. Fuller, Takeshi Sakai, L. Viktor Tóth, Tie Liu, Di Li, Tomoya Hirota, Miju Kang, Yuefang Wu, Charlotte Vastel, P. Sanhueza, Sheng-Yuan Liu, Jeong-Eun Lee, Kee-Tae Kim, Gwanjeong Kim, Naomi Hirano, Hee-Weon Yi, Ke Wang, Siyi Feng, Ken'ichi Tatematsu, and Department of Physics

Subjects
Library science, FOS: Physical sciences, INITIAL CONDITIONS, 01 natural sciences, GAS TEMPERATURE, STAR-FORMATION, DENSE CORES, Clouds, 0103 physical sciences, Natural science, China, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrochemistry, Z-MACHINE, Physics, 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Interstellar molecules, COLLAPSING PRESTELLAR CORES, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, Chinese academy of sciences, EVOLUTION, DARK CLOUDS, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), HYPERFINE-STRUCTURE, PRE-STELLAR CORES, Christian ministry
Abstract

We present the results of a single-pointing survey of 207 dense cores embedded in Planck Galactic Cold Clumps distributed in five different environments ($\lambda$ Orionis, Orion A, B, Galactic plane, and high latitudes) to identify dense cores on the verge of star formation for the study of the initial conditions of star formation. We observed these cores in eight molecular lines at 76-94 GHz using the Nobeyama 45-m telescope. We find that early-type molecules (e.g., CCS) have low detection rates and that late-type molecules (e.g., N$_2$H$^+$, c-C$_3$H$_2$) and deuterated molecules (e.g., N$_2$D$^+$, DNC) have high detection rates, suggesting that most of the cores are chemically evolved. The deuterium fraction (D/H) is found to decrease with increasing distance, indicating that it suffers from differential beam dilution between the D/H pair of lines for distant cores ($>$1 kpc). For $\lambda$ Orionis, Orion A, and B located at similar distances, D/H is not significantly different, suggesting that there is no systematic difference in the observed chemical properties among these three regions. We identify at least eight high D/H cores in the Orion region and two at high latitudes, which are most likely to be close to the onset of star formation. There is no clear evidence of the evolutionary change in turbulence during the starless phase, suggesting that the dissipation of turbulence is not a major mechanism for the beginning of star formation as judged from observations with a beam size of 0.04 pc., Comment: 55 pages, 12 Figures, 8 Tables, accepted for publication in ApJS

Published
2020
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29. The Chemical Structure of Young High-mass Star-forming Clumps. II. Parsec-scale CO Depletion and Deuterium Fraction of HCO +

Author

Hauyu Baobab Liu, Izaskun Jiménez-Serra, Guangxing Li, Qizhou Zhang, Zhi-Yu Zhang, Ken'ichi Tatematsu, P. Caselli, Di Li, Sheng-Yuan Liu, Henrik Beuther, Taylor Hogge, Xing Lu, Tie Liu, Patricio Sanhueza, J. Yuan, Olli Sipilä, Yu Wang, Siyi Feng, Y. C. Lin, Sarolta Zahorecz, Fujun Du, K. Wang, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Feng, S. [0000-0002-4707-8409], Li, D. [0000-0003-3010-7661], Caselli, P. [0000-0003-1481-7911], Du, F. [0000-0002-7489-0179], Lin, Y. [0000-0001-9299-5479, Sipilä, O. [0000-0002-9148-1625], Beuther, H. [0000-0002-1700-090X], Sanhueza, P. [0000-0002-7125-7685], Tatematsu, K. [0000-0002-8149-8546], Liu, S. Y. [0000-0003-4603-7119], Zhang, Q. [0000-0003-2384-6589], Wang, Y. [0000-0003-2226-4384], Hogge, T. [0000-0002-7211-7078], Jiménez Serra, I. [0000-0003-4493-8714], Lu, X. [0000-0003-2619-9305], Liu, T. [0000-0002-5286-2564], Wang, K. [0000-0002-7237-3856], Zhang, Z. Y. [0000-0002-7299-2876], Zahorecz, S. [0000-0001-6149-1278], Li, G. [0000-0003-3144-1952], Liu, H. B. [0000-0003-2300-2626], Yuan, J. [0000-0001-8060-3538], National Natural Science Foundation of China (NSFC), Max-Planck-Gesellschaft (MPG), European Research Council (ERC), Chinese Academy of Sciences (CAS), Agencia Estatal de Investigación (AEI), Japan Society for the Promotion of Science (JSPS), National Natural Science Foundation of China, 11988101 11873094 11973013 11721303, CAS International Partnership Program, 114A11KYSB20160008, Deutsche Forschungsgemeinschaft in the Collaborative Research Center 'The Milky Way System', SFB 881, One Hundred Person Project of the Chinese Academy of Sciences, 2017-089, Spanish FEDER, Ministry of Education Culture Sports, Japan Science and Technology, National Key Research and Development Program of China, 2017YFA0402702 2019YFA0405100, starting grant at the Kavli Institute for Astronomy and Astrophysics, 7101502016 Peking University, NAOJ ALMA Scientific Research grant, 2016-03B, and NAOJ Visiting Joint Research program, 1901-0403

Subjects
Astrochemistry, 010504 meteorology & atmospheric sciences, Chemical structure, FOS: Physical sciences, Fraction (chemistry), Astrophysics, Star (graph theory), 01 natural sciences, Parsec, Interstellar medium, Massive stars, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Star formation, Astronomy and Astrophysics, Interstellar molecules, Astrophysics - Astrophysics of Galaxies, Deuterium, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA)
Abstract

The physical and chemical properties of cold and dense molecular clouds are key to understanding how stars form. Using the IRAM 30 m and NRO 45 m telescopes, we carried out a Multiwavelength line-Imaging survey of the 70 $��$m dark and bright clOuds (MIAO). At a linear resolution of 0.1--0.5 pc, this work presents a detailed study of parsec-scale CO depletion and $\rm HCO^+$ deuterium (D-) fractionation toward four sources (G11.38+0.81, G15.22-0.43, G14.49-0.13, and G34.74-0.12) included in our full sample. In each source with $\rm T, accepted by ApJ

Published
2020
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30. Gravity and rotation drag the magnetic field in high-mass star formation

Author

Thomas Henning, Wouter Vlemmings, Siyi Feng, Juan D. Soler, Rolf Kuiper, Hendrik Linz, Patrick Hennebelle, A. Ahmadi, Henrik Beuther, C. Gieser, and Rowan J. Smith

Subjects
Physics, 010504 meteorology & atmospheric sciences, Star formation, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Physik (inkl. Astronomie), Polarization (waves), Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Magnetic field, Interstellar medium, Gravitation, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Drag, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Protostar, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences
Abstract

The formation of hot stars out of the cold interstellar medium lies at the heart of astrophysical research. Understanding the importance of magnetic fields during star formation remains a major challenge. With the advent of the Atacama Large Millimeter Array, the potential to study magnetic fields by polarization observations has tremendously progressed. However, the major question remains how much magnetic fields shape the star formation process or whether gravity is largely dominating. Here, we show that for the high-mass star-forming region G327.3 the magnetic field morphology appears to be dominantly shaped by the gravitational contraction of the central massive gas core where the star formation proceeds. We find that in the outer parts of the region, the magnetic field is directed toward the gravitational center of the region. Filamentary structures feeding the central core exhibit U-shaped magnetic field morphologies directed toward the gravitational center as well, again showing the gravitational drag toward the center. The inner part then shows rotational signatures, potentially associated with an embedded disk, and there the magnetic field morphology appears to be rotationally dominated. Hence, our results demonstrate that for this region gravity and rotation are dominating the dynamics and shaping the magnetic field morphology., Comment: 10 pages, 4 figures, accepted for the Astrophysical Journal, also available at https://www2.mpia-hd.mpg.de/homes/beuther/papers.html

Published
2020
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31. Chemical complexity in high-mass star formation: An observational and modeling case study of the AFGL 2591 VLA 3 hot core

Author

H. Linz, Peter Schilke, S. L. Lumsden, S. Leurini, Steven N. Longmore, T. Möller, A. Palau, S. Suri, Luca Moscadelli, M. T. Beltrán, Timea Csengeri, A. Ahmadi, Álvaro Sánchez-Monge, Siyi Feng, Rolf Kuiper, Luke T. Maud, P. Klaassen, Qizhou Zhang, D. Semenov, Roberto Galván-Madrid, F. Bosco, Friedrich Wyrowski, Henrik Beuther, Joseph C. Mottram, R. Pudritz, James Urquhart, T. Henning, T. Peters, C. Gieser, J. M. Winters, Karl M. Menten, Katharine G. Johnston, Izaskun Jiménez-Serra, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Kuiper, R. [0000-0003-2309-8963], Sánchez Monge, A. [0000-0002-3078-9482], Galván Madrid, R. [0000-0003-1480-4643], Leurini, S. [0000-0003-1014-3390], Ahmadi, A. [0000-0003-4037-5248], Semenov, D. [0000-0002-3913-7114], Gieser, C. [0000-0002-8120-1765], Deutsche Forschungsgemeinschaft (DFG), Agencia Estatal de Investigación (AEI), Ministerio de Economía y Competitividad (MINECO), European Research Council (ERC), Emmy Noether Research Group on Accretion Flows and Feedback in Realistic Models of Massive Star Formation - German Research Foundations (DFG), Programa de Apoyo a Proyectos de Investigacion e Innovacion Tecnologica de Mexico (PAPIIT), German Research Foundation (DFG), European Commission, and IRAM NOEMA Interferometer

Subjects
individual objects: AFGL 2591 [ISM], 010504 meteorology & atmospheric sciences, Mean kinetic temperature, Chemical process modeling, Core sample, FOS: Physical sciences, Astrophysics, Spatial distribution, 01 natural sciences, Spectral line, 0103 physical sciences, massive [Stars], Protostar, Molecule, QD, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), molecules [ISM], QC, 0105 earth and related environmental sciences, Astrochemistry, QB, Physics, GE, Star formation, Astronomy and Astrophysics, Physik (inkl. Astronomie), Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA)
Abstract

We present a detailed observational and modeling study of the hot core VLA 3 in the high-mass star-forming region AFGL 2591, which is a target region of the NOrthern Extended Millimeter Array (NOEMA) large program CORE. Using NOEMA observations at 1.37 mm with an angular resolution of ~0."42 (1 400 au at 3.33 kpc), we derived the physical and chemical structure of the source. We modeled the observed molecular abundances with the chemical evolution code MUSCLE (MUlti Stage ChemicaL codE). Results. With the kinetic temperature tracers CH3CN and H2CO we observe a temperature distribution with a power-law index of q = 0.41+-0.08. Using the visibilities of the continuum emission we derive a density structure with a power-law index of p = 1.7+-0.1. The hot core spectra reveal high molecular abundances and a rich diversity in complex molecules. The majority of the molecules have an asymmetric spatial distribution around the forming protostar(s), which indicates a complex physical structure on scales < 1 400 au. Using MUSCLE, we are able to explain the observed molecular abundance of 10 out of 14 modeled species at an estimated hot core chemical age of ~21 100 years. In contrast to the observational analysis, our chemical modeling predicts a lower density power-law index of p < 1.4. Reasons for this discrepancy are discussed. Conclusions. Combining high spatial resolution observations with detailed chemical modeling allows us to derive a concise picture of the physical and chemical structure of the famous AFGL 2591 hot core. The next steps are to conduct a similar analysis for the whole CORE sample, and then use this analysis to constrain the chemical diversity in high-mass star formation to a much greater depth., 22 pages, 13 figures, accepted for publication in A&A

Published
2019

32. Three dimensional projection effects on chemistry in a Planck galactic cold clump

Author

Diego Mardones, Jinhua He, J. X. Ge, Natalia Inostroza, Qiang Chang, Ken'ichi Tatematsu, Lei Zhu, Sheng-Yuan Liu, Tie Liu, Siyi Feng, Jonathan M. C. Rawlings, and Jeong-Eun Lee

Subjects
Physics, 010504 meteorology & atmospheric sciences, West china, FOS: Physical sciences, Library science, Astronomy and Astrophysics, 01 natural sciences, Chinese academy of sciences, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, East Asia, China, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Offsets of molecular line emission peaks from continuum peaks are very common but frequently difficult to explain with a single spherical cloud chemical model. We propose that the spatial projection effects of an irregular three dimensional (3D) cloud structure can be a solution. This work shows that the idea can be successfully applied to the Planck cold clump G224.4-0.6 by approximating it with four individual spherically symmetric cloud cores whose chemical patterns overlap with each other to produce observable line maps. With the empirical physical structures inferred from the observation data of this clump and a gas-grain chemical model, the four cores can satisfactorily reproduce its 850 $\mu$m continuum map and the diverse peak offsets of CCS, HC$_3$N and N$_2$H$^+$ simultaneously at chemical ages of about $8\times 10^5\sim 3\times 10^6$ yrs. The 3D projection effects on chemistry has the potential to explain such asymmetrical distributions of chemicals in many other molecular clouds., Comment: Accepted for publication in ApJ. 17 pages, 11 figures, 3 tables

Published
2019

33. SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution – Survey Description and Compact Source Catalogue

Author

Karine Demyk, Mark G. Rawlings, Giuseppe Cosentino, Lixia Yuan, Gwanjeong Kim, Dimitris Stamatellos, Satoshi Ohashi, Dalei Li, Yasuo Doi, L. Harvey-Smith, Archana Soam, Anthony Peter Whitworth, Mark Thompson, Izaskun Jiménez-Serra, Gary A. Fuller, Huei-Ru Chen, Tae-Geun Ji, Oscar Morata, Chakali Eswaraiah, Jinyi Yang, Takeshi Sakai, Y. L. Yuan, Hiroko Shinnaga, David Cornu, Jonathan Rawlings, Walter Kieran Gear, Shaila Akhter, Yuri Aikawa, A. Chrysostomou, Fanyi Meng, Andrew Walsh, Christine D. Wilson, P. M. McGehee, M. Chen, Tomoya Hirota, Carsten Henkel, You-Hua Chu, E. Falgarone, S. Kim, Yuxin He, Johanna Malinen, Sung-ju Kang, Chin-Fei Lee, Xuepeng Chen, Miju Kang, Annie Hughes, V.-M. Pelkonen, Graham S. Bell, Woojin Kwon, Huawei Zhang, Bon-Chul Koo, E. Jarken, Glenn J. White, J. X. Ge, Andrew Rigby, A-Ran Lyo, Wayne S. Holland, Hong-Li Liu, Geumsook Park, Mengyao Tang, Emily Drabek-Maunder, Hee-Weon Yi, M. Liu, Tie Liu, Rebeka Bögner, J.-P. Bernard, C. P. Zhang, B. S. Wang, Manash R. Samal, Harriet Parsons, Mika Juvela, Toby J. T. Moore, Lei Zhu, Ya-Wen Tang, Guobao Zhang, Leonardo Bronfman, George J. Bendo, S. Mairs, Serena Viti, H. Wang, Tetsuo Hasegawa, Yuxin Lin, Minho Choi, Zhiyuan Ren, Ke Wang, Yi-Jehng Kuan, David Eden, I. Ristorcelli, Lei Qian, X. Chen, Paul F. Goldsmith, Jinhua He, Diego Mardones, Shih-Ping Lai, Di Li, Soojong Pak, Qizhou Zhang, Ken'ichi Tatematsu, L. Montier, Yuefang Wu, C. Zhou, Guido Garay, Patricio Sanhueza, A. Rivera-Ingraham, Nicolas Peretto, Keping Qiu, Siyi Feng, Patrick M. Koch, Neal J. Evans, Jeong-Eun Lee, Andrew Blain, A. P. Marston, Hua-bai Li, M. Fich, Chao Zhang, Eun Jung Chung, G. Luo, J. Montillaud, Derek Ward-Thompson, Jianjun Zhou, Maria Cunningham, Jungha Kim, N. Lo, Roberta Paladini, J. Di Francesco, Jongsoo Kim, Ye Xu, Xing Lu, Charlotte Vastel, Chang Won Lee, Pak Shing Li, John A. P. Lopez, Per Friberg, Sheng-Li Qin, Gerald Moriarty-Schieven, D. Alina, G. Pech, Wen Ping Chen, O. Fehér, Pei Zuo, Sheng-Yuan Liu, Jinghua Yuan, Scott Chapman, Alessio Traficante, Doug Johnstone, Jane Greaves, Do-Young Byun, Naomi Hirano, Helen J. Fraser, Jiali Wang, Koji S. Kawabata, J. G. A. Wouterloot, X. Guan, Hsien Shang, Annie Zavagno, John Richer, Kee-Tae Kim, Sarolta Zahorecz, Kate Pattle, Y. Lee, L. V. Toth, Kevin Lacaille, Department of Physics, Particle Physics and Astrophysics, Liverpool John Moores University (LJMU), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), University of Arizona, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), and Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Milky Way, Continuum (design consultancy), SPIRAL ARMS, FOS: Physical sciences, F800, Astrophysics, 01 natural sciences, ISM: clouds, Luminosity, STAR-FORMATION, CLUMP IDENTIFICATION, symbols.namesake, surveys, 0103 physical sciences, Planck, GOULD BELT SURVEY, 010303 astronomy & astrophysics, James Clerk Maxwell Telescope, Solar and Stellar Astrophysics (astro-ph.SR), QC, QB, Physics, LEGACY SURVEY, Spiral galaxy, stars: formation, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], ATLASGAL, Astronomy and Astrophysics, Galactic plane, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, CLOUD, submillimetre: ISM, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], GAS, Astrophysics of Galaxies (astro-ph.GA), symbols, MILKY-WAY, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], COMPLETE SAMPLE
Abstract

We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE consists of 850-um continuum observations of 1235 Planck Galactic Cold Clumps (PGCCs) made with the Submillimetre Common-User Bolometer Array 2 on the James Clerk Maxwell Telescope. These data are at an angular resolution of 14.4 arcsec, significantly improving upon the 353-GHz resolution of Planck at 5 arcmin, and allowing for a catalogue of 3528 compact sources in 558 PGCCs. We find that the detected PGCCs have significant sub-structure, with 61 per cent of detected PGCCs having 3 or more compact sources, with filamentary structure also prevalent within the sample. A detection rate of 45 per cent is found across the survey, which is 95 per cent complete to Planck column densities of $N_{H_{2}}$ $>$ 5 $\times$ 10$^{21}$ cm$^{-2}$. By positionally associating the SCOPE compact sources with YSOs, the star formation efficiency, as measured by the ratio of luminosity to mass, in nearby clouds is found to be similar to that in the more distant Galactic Plane, with the column density distributions also indistinguishable from each other., 16 pages, 13 figures, 1 table. Accepted for publication in MNRAS

Published
2019
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34. Sulfur-bearing molecules in Orion KL

Author

Zhiyuan Ren, Hui Shi, G. X. Luo, Ningyu Tang, Sheng-Li Qin, Di Li, Y. Peng, and Siyi Feng

Subjects
Physics, 010504 meteorology & atmospheric sciences, chemistry.chemical_element, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Sulfur, Full width at half maximum, Astrophysics - Solar and Stellar Astrophysics, chemistry, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Molecule, Continuum (set theory), 010303 astronomy & astrophysics, Linear resolution, Order of magnitude, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Line (formation)
Abstract

We present an observational study of the sulfur (S)-bearing species towards Orion KL at 1.3 mm by combining ALMA and IRAM-30\,m single-dish data. At a linear resolution of $\sim$800 au and a velocity resolution of 1 $\mathrm{km\, s^{-1}\, }$, we have identified 79 molecular lines from 6 S-bearing species. In these S-bearing species, we found a clear dichotomy between carbon-sulfur compounds and carbon-free S-bearing species in various characteristics, e.g., line profiles, spatial morphology, and molecular abundances with respect to $\rm H_2$. Lines from the carbon-sulfur compounds (i.e., OCS, $^{13}$CS, H$_2$CS) exhibit spatial distributions concentrated around the continuum peaks and extended to the south ridge. The full width at half maximum (FWHM) linewidth of these molecular lines is in the range of 2 $\sim$ 11 $\mathrm{km\, s^{-1}\, }$. The molecular abundances of OCS and H$_2$CS decrease slightly from the cold ($\sim$68 K) to the hot ($\sim$176 K) regions. In contrast, lines from the carbon-free S-bearing species (i.e., SO$_2$, $^{34}$SO, H$_2$S) are spatially more extended to the northeast of mm4, exhibiting broader FWHM linewidths (15 $\sim$ 26 $\mathrm{km\, s^{-1}\, }$). The molecular abundances of carbon-free S-bearing species increase by over an order of magnitude as the temperature increase from 50 K to 100 K. In particular, $\mathrm{^{34}SO/^{34}SO_2}$ and $\mathrm{OCS/SO_2}$ are enhanced from the warmer regions ($>$100 K) to the colder regions ($\sim$50 K). Such enhancements are consistent with the transformation of SO$_2$ at warmer regions and the influence of shocks.

Published
2019
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35. Estimating the Impact of Decoupled Payments on Farm Production in Northern Ireland: An Instrumental Variable Fixed Effect Approach

Author

Kehinde Oluseyi Olagunju, Myles Patton, and Siyi Feng

Subjects
subsidy, Natural resource economics, Geography, Planning and Development, TJ807-830, Management, Monitoring, Policy and Law, TD194-195, Renewable energy sources, farm production, 0502 economics and business, Economics, Production (economics), Agricultural policy, GE1-350, Endogeneity, 050207 economics, Agricultural productivity, Environmental effects of industries and plants, Renewable Energy, Sustainability and the Environment, 05 social sciences, Instrumental variable, Subsidy, Fixed effects model, instrumental variable, Environmental sciences, 050202 agricultural economics & policy, Common Agricultural Policy, fixed effect
Abstract

The production stimulating impact of agricultural subsidies has been a well-debated topic in agricultural policy analysis for some decades. In light of the EU reform of the Common Agricultural Policy (CAP) in year 2005 in which agricultural subsidies were decoupled from current production decisions and the modification to this payment in 2015, this study investigates the impact of decoupled payments under these two reforms on livestock production in Northern Ireland. The study uses a farm-level panel dataset covering 2008&ndash, 2016 period and employs an instrumental variable fixed effect model to control for relevant sources of endogeneity bias. According to the empirical results, the production impacts of decoupled payments were positive and significant but with differential impacts across livestock production sectors, suggesting that decoupled payments still maintain a significant effect on agricultural production and provide an indication of the supply response to changes in decoupled payments.

Published
2020
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36. Core fragmentation and Toomre stability analysis of W3(H2O): A case study of the IRAM NOEMA large program CORE

Author

Luke T. Maud, S. Leurini, Friedrich Wyrowski, Steven N. Longmore, Timea Csengeri, Eric Keto, R. Pudritz, Frédérique Motte, Sarah Ragan, Peter Schilke, A. Ahmadi, Álvaro Sánchez-Monge, Joseph C. Mottram, M. T. Beltrán, F. Bosco, S. L. Lumsden, Sylvain Bontemps, A. Palau, Siyi Feng, T. Peters, Hans Zinnecker, Luca Moscadelli, Karl M. Menten, Rolf Kuiper, Henrik Beuther, P. Klaassen, Roberto Galván-Madrid, James Urquhart, H. Linz, R. Cesaroni, T. Henning, J. M. Winters, Katharine G. Johnston, Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), foreign laboratories (FL), CERN [Genève], FORMATION STELLAIRE 2018, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), College of Automation, Harbin Engineering University (HRBEU), Max-Planck-Institut für Radioastronomie (MPIFR), Swinburne University of Technology (Hawthorn campus), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and School of Physics

Subjects
010504 meteorology & atmospheric sciences, Binary number, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, law.invention, Telescope, Fragmentation (mass spectrometry), law, 0103 physical sciences, Perpendicular, Differential rotation, 010303 astronomy & astrophysics, QC, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, QB, Physics, Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Astrophysics of Galaxies, Wavelength, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Millimeter, Astrophysics::Earth and Planetary Astrophysics
Abstract

The fragmentation mode of high-mass molecular clumps and the properties of the central rotating structures surrounding the most luminous objects have yet to be comprehensively characterised. Using the IRAM NOrthern Extended Millimeter Array (NOEMA) and the IRAM 30-m telescope, the CORE survey has obtained high-resolution observations of 20 well-known highly luminous star-forming regions in the 1.37 mm wavelength regime in both line and dust continuum emission. We present the spectral line setup of the CORE survey and a case study for W3(H2O). At ~0.35" (700 AU at 2 kpc) resolution, the W3(H2O) clump fragments into two cores (West and East), separated by ~2300 AU. Velocity shifts of a few km/s are observed in the dense-gas tracer, CH3CN, across both cores, consistent with rotation and perpendicular to the directions of two bipolar outflows, one emanating from each core. The kinematics of the rotating structure about W3(H2O) W shows signs of differential rotation of material, possibly in a disk-like object. The observed rotational signature around W3(H2O) E may be due to a disk-like object, an unresolved binary (or multiple) system, or a combination of both. We fit the emission of CH3CN (12-11) K = 4-6 and derive a gas temperature map with a median temperature of ~165 K across W3(H2O). We create a Toomre Q map to study the stability of the rotating structures against gravitational instability. The rotating structures appear to be Toomre unstable close to their outer boundaries, with a possibility of further fragmentation in the differentially-rotating core W3(H2O) W. Rapid cooling in the Toomre-unstable regions supports the fragmentation scenario. Combining millimeter dust continuum and spectral line data toward the famous high-mass star-forming region W3(H2O), we identify core fragmentation on large scales, and indications for possible disk fragmentation on smaller spatial scales., Comment: 23 pages, 26 figures, accepted for publication in Astronomy and Astrophysics

Published
2018
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37. Magnetic fields at the onset of high-mass star formation

Author

Rowan J. Smith, Katharine G. Johnston, Thomas Henning, Hendrik Linz, Andrew Walsh, Siyi Feng, Wouter Vlemmings, Takeshi Sakai, Juan D. Soler, Rolf Kuiper, Henrik Beuther, and Ramprasad Rao

Subjects
FOS: Physical sciences, Astrophysics, 01 natural sciences, Spectral line, Polarization, 0103 physical sciences, Astronomy, Astrophysics and Cosmology, individual: IRDC18310 [Stars], 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), formation [Stars], Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Turbulence, Star formation, interferometers [Instrumentation], Astronomy and Astrophysics, Physik (inkl. Astronomie), Condensed Matter Physics, Critical value, Polarization (waves), Atacama Large Millimeter Array, Fusion, Plasma and Space Physics, Astrophysics - Astrophysics of Galaxies, Magnetic field, Wavelength, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Magnetic fields, clouds [ISM]
Abstract

Context: The importance of magnetic fields at the onset of star formation related to the early fragmentation and collapse processes is largely unexplored today. Aims: We want to understand the magnetic field properties at the earliest evolutionary stages of high-mass star formation. Methods: The Atacama Large Millimeter Array is used at 1.3mm wavelength in full polarization mode to study the polarized emission and by that the magnetic field morphologies and strengths of the high-mass starless region IRDC18310-4. Results: The polarized emission is clearly detected in four sub-cores of the region. In general it shows a smooth distribution, also along elongated cores. Estimating the magnetic field strength via the Davis-Chandrasekhar-Fermi method and following a structure function analysis, we find comparably large magnetic field strengths between ~0.6 and 3.7mG. Comparing the data to spectral line observations, the turbulent-to-magnetic energy ratio is low, indicating that turbulence does not significantly contribute to the stability of the gas clump. A mass-to-flux ratio around the critical value 1.0 - depending on column density - indicates that the region starts to collapse which is consistent with the previous spectral line analysis of the region. Conclusions: While this high-mass region is collapsing and thus at the verge of star formation, the high magnetic field values and the smooth spatial structure indicate that the magnetic field is important for the fragmentation and collapse process. This single case study can only be the starting point for larger sample studies of magnetic fields at the onset of star formation., 7 pages, 5 figures, Astronomy & Astrophysics in press, http://www.mpia.de/homes/beuther/papers.html

Published
2018
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38. Seeds of Life in Space (SOLIS). III. Zooming Into the Methanol Peak of the Prestellar Core L1544

Author

Jonathan Holdship, Ana Chacón-Tanarro, Ana López-Sepulcre, Vianney Taquet, Claudio Codella, J. Laas, D. Quenard, Francesco Fontani, P. Hily-Blant, Ali Jaber Al-Edhari, Cécile Favre, Linda Podio, Serena Viti, Nami Sakai, Yoko Oya, Leonardo Testi, Jaime E. Pineda, Patrice Theulé, J. Ospina-Zamudio, François Dulieu, Luca Bizzocchi, Emmanuel Caux, Albert Rimola, E. Bianchi, Roberto Neri, Nadia Balucani, Anton Vasyunin, Anna Punanova, Izaskun Jiménez-Serra, Rumpa Choudhury, Sandrine Bottinelli, Rafael Bachiller, Bertrand Lefloch, Piero Ugliengo, Claudine Kahane, Andy Pon, S. Spezzano, Satoshi Yamamoto, Felipe O. Alves, Cecilia Ceccarelli, Ian R. Sims, Siyi Feng, Charlotte Vastel, Paola Caselli, Ural Federal University [Ekaterinburg] (UrFU), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), Queen Mary University of London (QMUL), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), University of Western Ontario (UWO), INAF - Osservatorio Astrofisico di Arcetri (OAA), University of Electro-Communications [Tokyo] (UEC), Università degli Studi di Perugia (UNIPG), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Universitat Autònoma de Barcelona (UAB), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden [Leiden], Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Ortopedia e Medicina del Lavoro, Università degli Studi di Torino, 10126 Turin, European Research Council (ERC) [PALs 320620], CITA National Fellowship, STFC [ST/L004801, ST/M004139], STFC through an Ernest Rutherford Fellowship, ERC [DOC 741002], Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia = University of Perugia (UNIPG), Università degli Studi di Firenze = University of Florence (UniFI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, Università degli studi di Torino = University of Turin (UNITO), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze [Firenze], PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), and Universitat Autònoma de Barcelona [Barcelona] (UAB)

Subjects
ISM kinematics and dynamics, ISM individual objects (L1544), radio lines ISM, Thermodynamic equilibrium, Continuum (design consultancy), FOS: Physical sciences, ISM: clouds, 01 natural sciences, Molecular physics, ISM molecules, 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ISM: kinematics and dynamics, Physics, [PHYS]Physics [physics], ISM: individual objects (L1544), ISM: molecules, radio lines: ISM, stars: formation, Astronomy and Astrophysics, Space and Planetary Science, Accretion (meteorology), 010308 nuclear & particles physics, Velocity dispersion, Rotational temperature, Static core, Astrophysics - Astrophysics of Galaxies, stars formation, Core (optical fiber), ISM clouds, Astrophysics - Solar and Stellar Astrophysics, Astrophysics of Galaxies (astro-ph.GA), astrochimica, Order of magnitude
Abstract

Towards the pre-stellar core L1544, the methanol (CH$_3$OH) emission forms an asymmetric ring around the core centre, where CH$_3$OH is mostly in solid form, with a clear peak 4000~au to the north-east of the dust continuum peak. As part of the NOEMA Large Project SOLIS (Seeds of Life in Space), the CH$_3$OH peak has been spatially resolved to study its kinematics and physical structure and to investigate the cause behind the local enhancement. We find that methanol emission is distributed in a ridge parallel to the main axis of the dense core. The centroid velocity increases by about 0.2~km~s$^{-1}$ and the velocity dispersion increases from subsonic to transonic towards the central zone of the core, where the velocity field also shows complex structure. This could be indication of gentle accretion of material onto the core or interaction of two filaments, producing a slow shock. We measure the rotational temperature and show that methanol is in local thermodynamic equilibrium (LTE) only close to the dust peak, where it is significantly depleted. The CH$_3$OH column density, $N_{tot}({\rm CH_3OH})$, profile has been derived with non-LTE radiative transfer modelling and compared with chemical models of a static core. The measured $N_{tot}({\rm CH_3OH})$ profile is consistent with model predictions, but the total column densities are one order of magnitude lower than those predicted by models, suggesting that the efficiency of reactive desorption or atomic hydrogen tunnelling adopted in the model may be overestimated; or that an evolutionary model is needed to better reproduce methanol abundance., 19 pages, 18 figures. Accepted by ApJ

Published
2018
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39. Fragmentation and disk formation during high-mass star formation. IRAM NOEMA (Northern Extended Millimeter Array) large program CORE

Author

P. Klaassen, E. Keto, Siyi Feng, Friedrich Wyrowski, Joseph C. Mottram, Riccardo Cesaroni, Roberto Galván-Madrid, Sarah Ragan, Rolf Kuiper, Peter Schilke, S. L. Lumsden, M. T. Beltrán, A. Palau, Álvaro Sánchez-Monge, Qizhou Zhang, Melvin Hoare, Luke T. Maud, Timea Csengeri, Steven N. Longmore, Henrik Beuther, J. M. Winters, Katharine G. Johnston, T. Henning, S. Leurini, C. Gieser, Karl M. Menten, R. Pudritz, A. Ahmadi, H. Linz, D. A. Semenov, F. Bosco, T. Peters, and James Urquhart

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, law.invention, Gravitation, Telescope, Fragmentation (mass spectrometry), law, 0103 physical sciences, 010303 astronomy & astrophysics, QC, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, QB, Physics, 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Physik (inkl. Astronomie), Astrophysics - Astrophysics of Galaxies, Magnetic field, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Outflow, Millimeter
Abstract

Aims: We aim to understand the fragmentation as well as the disk formation, outflow generation and chemical processes during high-mass star formation on spatial scales of individual cores. Methods: Using the IRAM Northern Extended Millimeter Array (NOEMA) in combination with the 30m telescope, we have observed in the IRAM large program CORE the 1.37mm continuum and spectral line emission at high angular resolution (~0.4'') for a sample of 20 well-known high-mass star-forming regions with distances below 5.5kpc and luminosities larger than 10^4Lsun. Results: We present the overall survey scope, the selected sample, the observational setup and the main goals of CORE. Scientifically, we concentrate on the mm continuum emission on scales on the order of 1000AU. We detect strong mm continuum emission from all regions, mostly due to the emission from cold dust. The fragmentation properties of the sample are diverse. We see extremes where some regions are dominated by a single high-mass core whereas others fragment into as many as 20 cores. A minimum-spanning-tree analysis finds fragmentation at scales on the order of the thermal Jeans length or smaller suggesting that turbulent fragmentation is less important than thermal gravitational fragmentation. The diversity of highly fragmented versus singular regions can be explained by varying initial density structures and/or different initial magnetic field strengths. Conclusions: The smallest observed separations between cores are found around the angular resolution limit which indicates that further fragmentation likely takes place on even smaller spatial scales. The CORE project with its numerous spectral line detections will address a diverse set of important physical and chemical questions in the field of high-mass star formation., Comment: 29 pages, 17 figures, Astronomy & Astrophysics in press, for a higher-resolution version of the paper see http://www.mpia.de/homes/beuther/papers.html

Published
2018

40. Market Impact of Foot-and-Mouth Disease Control Strategies: A UK Case Study

Author

Myles Patton, Siyi Feng, and John B. Davis

Subjects
040301 veterinary sciences, Culling, Profit (economics), 0403 veterinary science, market impact, 0502 economics and business, Economic impact analysis, disease control strategy, health care economics and organizations, Original Research, lcsh:Veterinary medicine, General Veterinary, Cost–benefit analysis, Public economics, business.industry, Partial equilibrium, 05 social sciences, partial equilibrium model, 04 agricultural and veterinary sciences, economics, Agriculture, foot-and-mouth disease, lcsh:SF600-1100, Economic model, Veterinary Science, 050202 agricultural economics & policy, Business, Market impact
Abstract

Foot and Mouth Disease (FMD) poses a serious threat to the agricultural sector due to its highly contagious nature. Outbreaks of FMD can lead to substantial disruptions to livestock markets due to loss of production and access to international markets. In a previously FMD-free country, the use of vaccination to augment control of an FMD outbreak is increasingly being recognised as an alternative control strategy to direct slaughtering (Stamping-Out). The choice of control strategy has implications on production, trade and hence prices of the sector. Specific choice of eradication strategies depends on their costs and benefits. Economic impact assessments are often based on Benefit-Cost framework, which provide detailed information on the changes in profit for a farm or budget implications for a government (Rich et al., 2005). However, this framework cannot capture price effects caused by changes in: production due to culling of animals; access to international markets; and consumers’ reaction. These three impacts combine to affect equilibrium within commodity markets (Paarlberg et al., 2002). This paper provides assessment of sectoral level impacts of the eradication choices of FMD outbreaks, which are typically not available from Benefit-Cost framework, in the context of the UK. The FAPRI-UK model, a partial equilibrium model of the agricultural sector, is utilised to investigate market outcomes of different control strategies (namely, stamping-out, and vaccinate-to-die) in the case of FMD outbreaks. The outputs from the simulations of the EXODIS epidemiological model (number of animals culled/vaccinated and duration of outbreak) are used as inputs within the economic model to capture the overall price impact of the animal destruction, export ban and consumers’ response.

Published
2017

41. The Chemical Structure of Young High-mass Star-forming Clumps. I. Deuteration

Author

Ke Wang, P. Caselli, Siyi Feng, Olli Sipilä, Henrik Beuther, and Y. C. Lin

Subjects
Physics, 010504 meteorology & atmospheric sciences, Star formation, Chemical structure, Star (game theory), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Excited state, 0103 physical sciences, High mass, Isotopologue, Infrared dark cloud, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Order of magnitude, 0105 earth and related environmental sciences
Abstract

The chemical structure of high-mass star nurseries is important for a general understanding of star formation. Deuteration is a key chemical process in the earliest stages of star formation because its efficiency is sensitive to the environment. Using the IRAM-30 m telescope at 1.3--4.3 mm wavelengths, we have imaged two parsec-scale high-mass protostellar clumps (P1 and S) that show different evolutionary stages but are located in the same giant filamentary {infrared dark cloud} G28.34+0.06. Deep spectral images at subparsec resolution reveal the dust and gas physical structures of both clumps. We find that (1) the low-$J$ lines of $\rm N_2H^+$, HCN, HNC, and $\rm HCO^+$ isotopologues are subthermally excited; and (2) the deuteration of $\rm N_2H^+$ is more efficient than that of $\rm HCO^+$, HCN, and HNC by an order of magnitude. The deuterations of these species are enriched toward the chemically younger clump S compared with P1, indicating that this process favors the colder and denser environment ($\rm T_{kin} \sim14 K$, $\rm N(NH_3) \sim 9\times 10^{15}\,cm^{-2}$). In contrast, single deuteration of $\rm NH_3$ is insensitive to the environmental difference between P1 and S; and (3) single deuteration of $\rm CH_3OH$ ($\rm > 10\%$) is detected toward the location where CO shows a depletion of $\sim10$. This comparative chemical study between P1 and S links the chemical variations to the environmental differences and shows chemical similarities between the early phases of high- and low-mass star-forming regions.

Published
2019
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42. Alternative U.S. biofuel mandates and global GHG emissions: The role of land use change, crop management and yield growth

Author

Siyi Feng, Bruce A. McCarl, Aline Mosnier, Steven K. Rose, Petr Havlik, Uwe A. Schneider, Hugo Valin, Michael Obersteiner, Justin Baker, and Brian C. Murray

Subjects
Land use, business.industry, Renewable Fuel Standard, Management, Monitoring, Policy and Law, Agricultural economics, General Energy, Agricultural land, Bioenergy, Biofuel, Agriculture, Greenhouse gas, Environmental science, Land use, land-use change and forestry, business
Abstract

We investigate the impacts of the U.S. renewable fuel standard (RFS2) and several alternative biofuel policy designs on global GHG emissions from land use change and agriculture over the 2010–2030 horizon. Analysis of the scenarios relies on GLOBIOM, a global, multi-sectoral economic model based on a detailed representation of land use. Our results reveal that RFS2 would substantially increase the portion of agricultural land needed for biofuel feedstock production. U.S. exports of most agricultural products would decrease as long as the biofuel target would increase leading to higher land conversion and nitrogen use globally. In fact, higher levels of the mandate mean lower net emissions within the U.S. but when the emissions from the rest of the world are considered, the US biofuel policy results in almost no change on GHG emissions for the RFS2 level and higher global GHG emissions for higher levels of the mandate or higher share of conventional corn-ethanol in the mandate. Finally, we show that if the projected crop productivity would be lower globally, the imbalance between domestic U.S. GHG savings and additional GHG emissions in the rest of the world would increase, thus deteriorating the net global impact of U.S. biofuel policies.

Published
2013
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43. Seeds of Life in Space (SOLIS): I. Carbon-chain growth in the Solar-type protocluster OMC2-FIR4

Author

Rafael Bachiller, S. Spezzano, Jaime E. Pineda, Emmanuel Caux, Paola Caselli, Bertrand Lefloch, Piero Ugliengo, Yoko Oya, Audrey Coutens, Claudio Codella, Serena Viti, Claudine Kahane, Andy Pon, Jonathan Holdship, R. Neri, R. Choudhury, P. Hily-Blant, Patrice Theulé, Jacob C. Laas, Anton Vasyunin, Sandrine Bottinelli, A. Jaber Al-Edhari, Francesco Fontani, Izaskun Jiménez-Serra, Linda Podio, Felipe O. Alves, François Dulieu, Laurent Wiesenfeld, Cecilia Ceccarelli, D. Quénard, Satoshi Yamamoto, Cécile Favre, Ian R. Sims, Leonardo Testi, Vianney Taquet, Luca Bizzocchi, Nami Sakai, Ana López-Sepulcre, Albert Rimola, Nadia Balucani, E. Bianchi, Ana Chacón-Tanarro, Anna Punanova, Siyi Feng, C. Vastel, INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia (UNIPG), Università degli Studi di Firenze [Firenze], Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), University College of London [London] (UCL), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Universitat Autònoma de Barcelona [Barcelona] (UAB), Queen Mary University of London (QMUL), University of Western Ontario (UWO), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Universiteit Leiden [Leiden], Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Ural Federal University [Ekaterinburg] (UrFU), University of Electro-Communications [Tokyo] (UEC), Physique et Chimie du Milieu Interstellaire (PCMI) - Conseil National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales (CNES), LabeX Osug (Investissements d'avenir) [ANR10LABX56], Canadian Institute for Theoretical Astrophysics (CITA), European Research Council [PALs 320620], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Universitat Autònoma de Barcelona (UAB), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia = University of Perugia (UNIPG), Università degli Studi di Firenze = University of Florence (UniFI), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, and Università degli studi di Torino = University of Turin (UNITO)

Subjects
010504 meteorology & atmospheric sciences, radio lines ISM, CHEMICAL MODEL, chemistry.chemical_element, Flux, Astrophysics, 01 natural sciences, 7. Clean energy, star formation, MOLECULES, ISM molecules, ABUNDANCE RATIOS, FORMATION [STARS], 0103 physical sciences, Cluster (physics), CHAINS, 010303 astronomy & astrophysics, INTERSTELLAR MEDIUMS, ComputingMilieux_MISCELLANEOUS, Radio lines: ISM, 0105 earth and related environmental sciences, Line (formation), Physics, [PHYS]Physics [physics], EASTERN REGIONS, ISM: Molecules, Stars: Formation, Astronomy and Astrophysics, Space and Planetary Science, IONISATION RATES, Star formation, ISM [RADIO LINES], COSMIC RAYS, Galaxy, Interstellar medium, Stars, chemistry, 13. Climate action, MOLECULES [ISM], COSMOLOGY, IONIZATION, Molecular physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Carbon, STARS
Abstract

The interstellar delivery of carbon atoms locked into molecules might be one of the key ingredients for the emergence of life. Cyanopolyynes are carbon chains delimited at their two extremities by an atom of hydrogen and a cyano group, meaning that they could be excellent reservoirs of carbon. The simplest member, HC3N, is ubiquitous in the galactic interstellar medium and found also in external galaxies. Thus, understanding the growth of cyanopolyynes in regions forming stars similar to our Sun, and what affects them, is particularly relevant. In the framework of the IRAM/NOEMA Large Program SOLIS (Seeds Of Life In Space), we have obtained a map of two cyanopolyynes, HC3N and HC5N, in the protocluster OMC-2 FIR4. Because our Sun is thought to be born in a rich cluster, OMC-2 FIR4 is one of the closest and best known representatives of the environment in which the Sun may have been born. We find a HC3N/HC5N abundance ratio across the source in the range 1..30, with the smallest values (≤10) in FIR5 and in the eastern region of FIR4. The ratios ≤10 can be reproduced by chemical models only if: (1) the cosmic-ray ionisation rate is ∼4× 10-14 s-1; (2) the gaseous elemental ratio C/O is close to unity; and (3) oxygen and carbon are largely depleted. The large is comparable to that measured in FIR4 by previous works and was interpreted as due to a flux of energetic (≥10 MeV) particles from embedded sources. We suggest that these sources could lie east of FIR4 and FIR5. A temperature gradient across FIR4, with T decreasing from east to west by about 10 K, could also explain the observed change in the HC3N/HC5N line ratio, without the need of a cosmic ray ionisation rate gradient. However, even in this case, a high constant cosmic-ray ionisation rate (of the order of 10s s-1) is necessary to reproduce the observations. © ESO 2017. European Research Council, ERC: PALs 320620 Centre National dâ Etudes Spatiales, CNES ANR10LABX56 Canadian Institute for Theoretical Astrophysics, ICAT Conseil National de la Recherche Scientifique, CNRS-L ★ Based on observations carried out under project number L15AA with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). ★★ The final IRAM data used in the paper (FITS format) are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A57 Acknowledgements. We thank the IRAM staff for their help in the data reduction. Many thanks to the anonymous referee for his/her constructive comments. This work was supported by the French program Physique et Chimie du Milieu In-terstellaire (PCMI) funded by the Conseil National de la Recherche Scientifique (CNRS) and Centre National d’Études Spatiales (CNES), and by a grant from LabeX Osug@2020 (Investissements d’avenir – ANR10LABX56). Partial salary support for A. Pon was provided by a Canadian Institute for Theoretical Astrophysics (CITA) National Fellowship. P.C., A. Punanova, A.C., and J.E.P. acknowledge support from the European Research Council (project PALs 320620). C.F. acknowledges founding from French space agency CNES.

Published
2017
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44. Seeds of Life in Space (SOLIS). II. Formamide in protostellar shocks: Evidence for gas-phase formation

Author

Izaskun Jiménez-Serra, Ana Chacón-Tanarro, Claudine Kahane, Andy Pon, R. Neri, Yoko Oya, Patrice Theulé, Leonardo Testi, Audrey Coutens, Paola Caselli, Charlotte Vastel, Serena Viti, François Dulieu, Jaime E. Pineda, R. Choudhury, P. Hily-Blant, J. Ospina, Fanny Vazart, Vincenzo Barone, Ana López-Sepulcre, Ian R. Sims, Laurent Wiesenfeld, Claudio Codella, Anna Punanova, Sandrine Bottinelli, Vianney Taquet, Francesco Fontani, Jacob C. Laas, A. Jaber Al-Edhari, Linda Podio, Cecilia Ceccarelli, Satoshi Yamamoto, Nami Sakai, Felipe O. Alves, Rafael Bachiller, Emmanuel Caux, S. Spezzano, D. Quénard, Nadia Balucani, Siyi Feng, Cécile Favre, Luca Bizzocchi, Cristina Puzzarini, Bertrand Lefloch, Piero Ugliengo, Anton Vasyunin, Jonathan Holdship, Dimitrios Skouteris, Albert Rimola, E. Bianchi, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Università degli Studi di Perugia (UNIPG), INAF - Osservatorio Astronomico di Brera (OAB), Southern University of Science and Technology [Shenzhen] (SUSTech), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Queen Mary University of London (QMUL), University College of London [London] (UCL), ESAB, Universitad polytecnica de Cataluna, University of Western Ontario (UWO), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), departament de Quimica, Universitat Autònoma de Barcelona [Barcelona] (UAB), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Scuola Normale Superiore di Pisa (SNS), European Southern Observatory (ESO), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Codella, C., Ceccarelli, C., Caselli, P., Balucani, N., Barone, V., Fontani, F., Lefloch, B., Podio, L., Viti, S., Feng, S., Bachiller, R., Bianchi, E., Dulieu, F., Jiménez-Serra, I., Holdship, J., Neri, R., Pineda, J.E., Pon, A., Sims, I., Spezzano, S., Vasyunin, A.I., Alves, F., Bizzocchi, L., Bottinelli, S., Caux, E., Chacón-Tanarro, A., Choudhury, R., Coutens, A., Favre, C., Hily-Blant, P., Kahane, C., Jaber Al-Edhari, A., Laas, J., López-Sepulcre, A., Ospina, J., Oya, Y., Punanova, A., Puzzarini, C., Quenard, D., Rimola, A., Sakai, N., Skouteris, D., Taquet, V., Testi, L., Theulé, P., Ugliengo, P., Vastel, C., Vazart, F., Wiesenfeld, L., Yamamoto, S., Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Perugia = University of Perugia (UNIPG), Southern University of Science and Technology (SUSTech), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universitat Autònoma de Barcelona (UAB), Università degli studi di Torino = University of Turin (UNITO), Pineda, J. E., Vasyunin, A. I., Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)

Subjects
Formamide, Abundance (chemistry), Direct evidence, Stars: formation, FOS: Physical sciences, Context (language use), Astrophysics, ISM: molecule, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, Protostar, molecule [ISM], 010303 astronomy & astrophysics, ISM: jets and outflow, formation [Stars], ComputingMilieux_MISCELLANEOUS, Line (formation), Earth and Planetary Astrophysics (astro-ph.EP), ISM: individual objects: L1157-B1, ISM: jets and outflows, ISM: molecules, Astronomy and Astrophysics, Space and Planetary Science, Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, jets and outflow [ISM], individual objects: L1157-B1 [ISM], Astronomy and Astrophysic, Stars, chemistry, Millimeter, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract

Context: Modern versions of the Miller-Urey experiment claim that formamide (NH$_2$CHO) could be the starting point for the formation of metabolic and genetic macromolecules. Intriguingly, formamide is indeed observed in regions forming Solar-type stars as well as in external galaxies. Aims: How NH$_2$CHO is formed has been a puzzle for decades: our goal is to contribute to the hotly debated question of whether formamide is mostly formed via gas-phase or grain surface chemistry. Methods: We used the NOEMA interferometer to image NH$_2$CHO towards the L1157-B1 blue-shifted shock, a well known interstellar laboratory, to study how the components of dust mantles and cores released into the gas phase triggers the formation of formamide. Results: We report the first spatially resolved image (size $\sim$ 9", $\sim$ 2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM $\simeq$ 5 km s$^{-1}$. A column density of $N_{\rm NH_2CHO}$ = 8 $\times$ 10$^{12}$ cm$^{-1}$, and an abundance (with respect to H-nuclei) of 4 $\times$ 10$^{-9}$ are derived. We show a spatial segregation of formamide with respect to other organic species. Our observations, coupled with a chemical modelling analysis, indicate that the formamide observed in L1157-B1 is formed by gas-phase chemical process, and not on grain surfaces as previously suggested. Conclusions: The SOLIS interferometric observations of formamide provide direct evidence that this potentially crucial brick of life is efficiently formed in the gas-phase around Sun-like protostars., 7 pages, 1 table, 5 figures, A&A Letters, in press

Published
2017
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45. Multiplicity and disks within the high-mass core NGC7538IRS1: Resolving cm line and continuum emission at ~0.06'x0.05' resolution

Author

H. Linz, Th. Henning, Henrik Beuther, Richard Teague, and Siyi Feng

Subjects
Physics, Continuum (measurement), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, High mass, Astrophysics::Earth and Planetary Astrophysics, Multiplicity (chemistry), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Context: High-mass stars have a high degree of multiplicity and most likely form via disk accretion processes. The detailed physics of the binary and disk formation are still poorly constrained. Methods: Using the VLA in its most extended configuration at ~24GHz toward the prototypical high-mass star-forming region NGC7538IRS1 has allowed us to study the NH3 and thermal CH3OH emission and absorption as well as the cm continuum emission at an unprecedented spatial resolution of 0.06"x0.05", corresponding to a linear resolution of ~150AU at a distance of 2.7kpc. Results: A comparison of these new cm continuum data with previous VLA observations from 23yrs ago reveals no recognizable proper motions. If the emission were caused by a protostellar jet, proper motion signatures should have been easily identified. In combination with the high spectral indices S~nu^{alpha} (alpha between 1 and 2), this allows us to conclude that the continuum emission is from two hypercompact HII regions separated in projection by about 430AU. The NH3 spectral line data reveal a common rotating envelope indicating a bound high-mass binary system. In addition to this, the thermal CH3OH data show two separate velocity gradients across the two hypercompact HII regions. This indicates two disk-like structures within the same rotating circumbinary envelope. Disk and envelope structures are inclined by ~33deg, which can be explained by initially varying angular momentum distributions within the natal, turbulent cloud. Conclusions: Studying high-mass star formation at sub-0.1" resolution allows us to isolate multiple sources as well as to separate circumbinary from disk-like rotating structures., Comment: 11 pages, 9 figures, Astronomy & Astrophysics in press, a higher-resolution version can be found at http://www.mpia.de/homes/beuther/papers.html

Published
2017
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46. Seeds Of Life In Space (SOLIS): The Organic Composition Diversity at 300-1000 au Scale in Solar-type Star-forming Regions

Author

R. Choudhury, Emmanuel Caux, Felipe O. Alves, Jacob C. Laas, Albert Rimola, François Dulieu, Satoshi Yamamoto, Charlotte Vastel, Francesco Fontani, Serena Viti, Anton Vasyunin, Leonardo Testi, E. Bianchi, Jonathan Holdship, Ana Chacón-Tanarro, Nami Sakai, P. Hily-Blant, J. Ospina, Sandrine Bottinelli, Claudine Kahane, Andy Pon, D. Quénard, Bertrand Lefloch, Piero Ugliengo, Laurent Wiesenfeld, Ana López-Sepulcre, R. Neri, Rafael Bachiller, Cecilia Ceccarelli, Jaime E. Pineda, Claudio Codella, Vianney Taquet, Cécile Favre, Paola Caselli, Anna Punanova, A. Jaber Al-Edhari, Patrice Theulé, Linda Podio, S. Spezzano, Luca Bizzocchi, Yoko Oya, Audrey Coutens, Siyi Feng, Nadia Balucani, Ian R. Sims, Izaskun Jiménez-Serra, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astrofisico di Arcetri (OAA), Queen Mary University of London (QMUL), University College of London [London] (UCL), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia (UNIPG), Università degli Studi di Firenze [Firenze], Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), University of Western Ontario (UWO), Universitat Autònoma de Barcelona [Barcelona] (UAB), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Ural Federal University [Ekaterinburg] (UrFU), Centre National de la Recherche Scientifique (CNRS), University of Electro-Communications [Tokyo] (UEC), European Research Council (ERC) [320620, 741002], French program Physique et Chimie du Milieu Interstellaire (PCMI) - Conseil National de la Recherche Scientifique (CNRS), Centre National dEtudes Spatiales (CNES), Italian Ministero dell'Istruzione, Universita e Ricerca, through the grant Progetti Premiali iALMA [CUP C52I13000140001], Canadian Institute for Theoretical Astrophysics (CITA) National Fellowship, STFC [ST/L004801, ST/M004139], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia = University of Perugia (UNIPG), Università degli Studi di Firenze = University of Florence (UniFI), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universitat Autònoma de Barcelona (UAB), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino = University of Turin (UNITO), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Max-Planck-Institut fur Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany, INAF-Osservatorio Astrofisico di Arcetri (INAF-OAA), Institut de RadioAstronomie Millimétrique (IRAM), Department of Physics and Astronomy, University College London, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Observatorio Astronómico Nacional, Observatorio de Madrid, Alfonso XII (OAN), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Molécules dans l'Univers, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA (UMR_8112)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), University of AL-Muthanna, College of Science, Physics Department, AL-Muthanna, Iraq, Department of Physics, University of Tokyo, Departament de Quimica, Universitat Autonoma de Barcelona, E-08193 Bellaterra, Spain, RIKEN The Institute of Physical and Chemical Research, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
radio lines ISM, FOS: Physical sciences, Scale (descriptive set theory), Astrophysics, Type (model theory), Star (graph theory), Space (mathematics), ISM: clouds, 01 natural sciences, ISM: abundances, Spectral line, ISM molecules, Abundance (ecology), ISM: molecules, radio lines: ISM, Astronomy and Astrophysics, Space and Planetary Science, 0103 physical sciences, 14. Life underwater, 010303 astronomy & astrophysics, ISM abundances, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, Astrophysics - Astrophysics of Galaxies, Interstellar medium, ISM clouds, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Astrophysics of Galaxies (astro-ph.GA), Molecular physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Order of magnitude
Abstract

Complex organic molecules have been observed for decades in the interstellar medium. Some of them might be considered as small bricks of the macromolecules at the base of terrestrial life. It is hence particularly important to understand organic chemistry in Solar-like star forming regions. In this article, we present a new observational project: SOLIS (Seeds Of Life In Space). This is a Large Project at the IRAM-NOEMA interferometer, and its scope is to image the emission of several crucial organic molecules in a sample of Solar-like star forming regions in different evolutionary stage and environments. Here, we report the first SOLIS results, obtained from analysing the spectra of different regions of the Class 0 source NGC1333-IRAS4A, the protocluster OMC-2 FIR4, and the shock site L1157-B1. The different regions were identified based on the images of formamide (NH2CHO) and cyanodiacetylene (HC5N) lines. We discuss the observed large diversity in the molecular and organic content, both on large (3000-10000 au) and relatively small (300-1000 au) scales. Finally, we derive upper limits to the methoxy fractional abundance in the three observed regions of the same order of magnitude of that measured in few cold prestellar objects, namely ~10^-12-10^-11 with respect to H2 molecules., Comment: Accepted for publication on The Astrophysical Journal

Published
2017
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47. Outflow detection in a 70 $\mu$m dark high-mass core

Author

Qizhou Zhang, Keping Qiu, Zhi-Yu Zhang, Siyi Feng, Ke Wang, Hauyu Baobab Liu, and Henrik Beuther

Subjects
Physics, 010504 meteorology & atmospheric sciences, Resolution (mass spectrometry), Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Luminosity, Core (optical fiber), Red shift, Space and Planetary Science, 0103 physical sciences, High mass, Protostar, Outflow, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Cosmic dust
Abstract

We present observations towards a high-mass ($\rm >40\,M_{\odot}$), low luminosity ($\rm, Comment: 8 pages, 3 figures, submitted to ApJ on Jan. 18th, 2016, accepted on May. 5th, 2016

Published
2016

48. Are Infrared Dark Clouds Really Quiescent?

Author

Rowan J. Smith, Qizhou Zhang, Henrik Beuther, Thomas Henning, Siyi Feng, Sarah Ragan, and Hendrik Linz

Subjects
Physics, 010308 nuclear & particles physics, Infrared, Star formation, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Submillimeter Array, Astrophysics - Astrophysics of Galaxies, Ion, Stars, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, 010303 astronomy & astrophysics, Multiplet, Jeans instability, Hyperfine structure, QB
Abstract

The dense, cold regions where high-mass stars form are poorly characterised, yet they represent an ideal opportunity to learn more about the initial conditions of high-mass star formation (HMSF), since high-mass starless cores (HMSCs) lack the violent feedback seen at later evolutionary stages. We present continuum maps obtained from the Submillimeter Array (SMA) interferometry at 1.1 mm for four infrared dark clouds (IRDCs, G28.34S, IRDC 18530, IRDC 18306, and IRDC 18308). We also present 1 mm/3 mm line surveys using IRAM 30 m single-dish observations. Our results are: (1) At a spatial resolution of 10^4 AU, the 1.1 mm SMA observations resolve each source into several fragments. The mass of each fragment is on average >10 Msun, which exceeds the predicted thermal Jeans mass of the whole clump by a factor of up to 30, indicating that thermal pressure does not dominate the fragmentation process. Our measured velocity dispersions in the 30 m lines imply that non-thermal motions provides the extra support against gravity in the fragments. (2) Both non-detection of high-J transitions and the hyperfine multiplet fit of N2H+(1-0), C2H(1-0), HCN(1-0), and H13CN(1-0) indicate that our sources are cold and young. However, obvious detection of SiO and the asymmetric line profile of HCO+(1-0) in G28.34S indicate a potential protostellar object and probable infall motion. (3) With a large number of N-bearing species, the existence of carbon rings and molecular ions, and the anti-correlated spatial distributions between N2H+/NH2D and CO, our large-scale high-mass clumps exhibit similar chemical features as small-scale low-mass prestellar objects. This study of a small sample of IRDCs illustrates that thermal Jeans instability alone cannot explain the fragmentation of the clump into cold (~15 K), dense (>10^5 cm-3) cores and that these IRDCs are not completely quiescent., 32 pages, 9 figures

Published
2016

50. Empirical analysis of differential spillover effects within a growth equilibrium framework: Urban-rural versus rural-rural linkages

Author

Siyi Feng and Myles Patton

Subjects
Economic growth, Rural economy, 05 social sciences, Geography, Planning and Development, 0211 other engineering and technologies, 0507 social and economic geography, 021107 urban & regional planning, Differential (mechanical device), 02 engineering and technology, Environmental Science (miscellaneous), Northern ireland, Spillover effect, Spatial spillover, Economics, Population growth, Economic geography, 050703 geography
Abstract

The employment and population growth equilibrium model is extended to allow for differentiated linkages between rural and urban regions and among rural regions. The model is applied to examine the regional disparities within the rural economy of Northern Ireland between 2001 and 2007. To represent the theoretical idea of commuter shed, commuting data are used to construct the spatial weighting matrix. The results reveal positive rural–urban but negative rural-rural linkages, suggesting that rural regions benefit from economic growth in urban regions but compete with each other. The direct and indirect spillover effects are shown using simulation examples.

Published
2016
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