Search

We prepared a sample of mono-deuterated oxirane and studied its rotational spectrum in the laboratory between 490 GHz and 1060 GHz in order to improve its spectroscopic parameters and consequently the calculated rest frequencies of its rotational transitions. The updated rest frequencies were employed to detect $c$-C$_2$H$_3$DO for the first time in the interstellar medium in the Atacama Large Millimetre/submillimetre Array (ALMA) Protostellar Interferometric Line Survey (PILS) of the Class 0 protostellar system IRAS 16293$-$2422. Fits of the detected lines using the rotation diagrams yield a temperature of $T_{\rm rot} = 103 \pm 19$ K, which in turn agrees well with 125 K derived for the $c$-C$_2$H$_4$O main isotopologue previously. The $c$-C$_2$H$_3$DO to $c$-C$_2$H$_4$O ratio is found to be $\sim$0.15 corresponding to a D-to-H ratio of $\sim$0.036 per H atom which is slightly higher than the D-to-H ratio of species such as methanol, formaldehyde, ketene and but lower than those of the larger complex organic species such as ethanol, methylformate and glycolaldehyde. This may reflect that oxirane is formed fairly early in the evolution of the prestellar cores. The identification of doubly deuterated oxirane isotopomers in the PILS data may be possible judged by the amount of mono-deuterated oxirane and the observed trend that multiply deuterated isotopologues have higher deuteration rates than their mono-deuterated variants., Comment: 10 pages total; Mon. Not. R. Astron. Soc., accepted

Context. The abundances of deuterated molecules with respect to their main isotopologue counterparts have been determined to be orders of magnitude higher than expected from the cosmic abundance of deuterium relative to hydrogen. The increasing number of singly and multi-deuterated species detections helps us to constrain the interplay between gas-phase and solid-state chemistry and to understand better deuterium fractionation in the early stages of star formation. Acetaldehyde is one of the most abundant complex organic molecules (COMs) in star-forming regions and its singly deuterated isotopologues have already been observed towards protostars. Aims. A spectroscopic catalogue for astrophysical purposes is built for doubly deuterated acetaldehyde (CHD2CHO) from measurements in the laboratory. With this accurate catalogue, we aim to search for and detect this species in the interstellar medium and retrieve its column density and abundance. Methods. Sub-millimetre wave transitions were measured for the non-rigid doubly deuterated acetaldehyde CHD2CHO displaying hindered internal rotation of its asymmetrical CHD2 methyl group. An analysis of a dataset consisting of previously measured microwave transitions and of the newly measured ones was carried out with an effective Hamiltonian which accounts for the tunnelling of the asymmetrical methyl group. Results. A line position analysis was carried out, allowing us to reproduce 853 transition frequencies with a weighted root mean square standard deviation of 1.7, varying 40 spectroscopic constants. A spectroscopic catalogue for astrophysical purposes was built from the analysis results. Using this catalogue, we were able to detect, for the first time, CHD2CHO towards the low-mass proto-stellar system IRAS 16293-2422 utilising data from the ALMA Proto-stellar Interferometric Line Survey. Conclusions. The first detection of the CHD2CHO species allowed for the derivation of its column density with a value of 1.3×1015 cm−2 and an uncertainty of 10–20%. The resulting D2/D ratio of ~20% is found to be coincident with D2/D ratios derived for other COMs towards IRAS 16293-2422, pointing to a common formation environment with enhanced deuterium fractionation.

The molecule studied in this work, 2-hydroxyprop-2-enal, is among the candidates to be searched for in the interstellar medium (ISM), as it is a dehydration product of C3 sugars and contains structural motifs typical for some interstellar molecules. The aim of this work is to deepen knowledge about the millimetre-wave spectrum of 2-hydroxyprop-2-enal in the region enabling its search towards astronomical objects. We target the solar-type protostar IRAS16293-2422 and star-forming region Sagittarius (Sgr) B2(N). The rotational spectrum of 2-hydroxyprop-2-enal was measured and analysed in the frequency regions of 128-166 GHz and 285-329 GHz. The interstellar exploration towards IRAS16293-2422 was based on the Atacama Large Millimeter/submillimeter Array (ALMA) data of the Protostellar Interferometric Line Survey. We also used the imaging spectral line survey ReMoCA performed with ALMA toward Sgr B2(N). We modelled the astronomical spectra under the assumption of local thermodynamic equilibrium. We provide analysis of hundreds of rotational transitions of 2-hydroxyprop-2-enal in the ground state and the lowest lying excited vibrational state. We report its nondetection towards IRAS16293 B. The 2-hydroxyprop-2-enal/3-hydroxypropenal abundance ratio is estimated to be less-than or similar to 0.9-1.3 in agreement with the predicted value of 1.4. We also report the nondetection of 2-hydroxyprop-2-enal toward the hot molecular core Sgr B2(N1). We did not detect the related aldehydes 2-hydroxypropanal and 3-hydroxypropenal either. We find that these three molecules are at least 9, 4, and 10 times less abundant than acetaldehyde in this source, respectively. Despite the nondetections, the results of this work represent a significant improvement on previous investigations in the microwave region and meets the requirements for further searches of this molecule in the ISM., Accepted for publication in A&A

5 pags., 3 figs., 1 tab., In recent years we have seen an important increase in the number of protonated molecules detected in cold dense clouds. Here we report the detection in TMC-1 of HCCNCH+, the protonated form of HCCNC, which is a metastable isomer of HC3N. This is the first protonated form of a metastable isomer detected in a cold dense cloud. The detection was based on observations carried out with the Yebes 40m and IRAM 30m telescopes, which revealed four harmonically related lines. We derive a rotational constant B = 4664.431891 +/- 0.000692 MHz and a centrifugal distortion constant D = 519.14 +/- 4.14 Hz. From a high-level ab initio screening of potential carriers we confidently assign the series of lines to the ion HCCNCH+. We derive a column density of (3.0 +/- 0.5)e10 cm-2 for HCCNCH+, which results in a HCCNCH+/HCCNC abundance ratio of 0.010 +/- 0.002. This value is well reproduced by a state-of-the-art chemical model, which however is subject to important uncertainties regarding the chemistry of HCCNCH+. The observational and theoretical status of protonated molecules in cold dense clouds indicate that there exists a global trend in which protonated-to-neutral abundance ratios MH+/M increase with increasing proton affinity of the neutral M, although if one restricts to species M with high proton affinities (>700 kJ/mol), MH+/M ratios fall in the range 0.001-0.1, with no apparent correlation with proton affinity. We suggest various protonated molecules that are good candidates for detection in cold dense clouds in the near future., We acknowledge funding support from Spanish Ministerio de Ciencia e Innovación through grants PID2019-106110GB-I00, PID2019-107115GB-C21, and PID2019-106235GB-I00 and from the European Research Council (ERC Grant 610256: NANOCOSMOS).

5 pags., 3 figs., 2 tabs., We report the detection of the protonated form of HC7N in TMC-1. The discovery of the cation HC7NH+ was carried out via the observation of nine harmonically related lines in the Q-band using the Yebes 40 m radiotelescope. The observed frequencies allowed us to obtain the rotational constants B0 = 553.938802 (160) MHz and D0 = 3.6292 (705) Hz. The identification of HC7NH+ is further supported by accurate ab initio calculations. We derived a column density of (5.5 ± 0.7) × 1010 cm-2, which constitutes another piece of evidence for the identification of the carrier. In addition, we revised the HC7N column density and we derived a new value of (2.1 ± 0.2) × 1013 cm-2. Hence, the abundance ratio HC7N/HC7NH+ is ∼380, while those for HC3N/HC3NH+ and HC5N/HC5NH+ are ∼230 and ∼240, respectively. Here, we discuss these results within the framework of a chemical model for protonated molecules in cold dense clouds., We thank ERC for funding through grant ERC-2013-Syg610256-NANOCOSMOS. The Spanish authors thank Ministerio de Ciencia e Innovación for funding support through projects PID2019-106235GB-I00 and PID2019-107115GB-C21/AEI/10.13039/501100011033. M.A. thanks Ministerio de Ciencia e Innovación for grant RyC-2014-16277.

C. Vastel et al., [Aims] Methanol is a ubiquitous species commonly found in the molecular interstellar medium. It is also a crucial seed species for the build-up of chemical complexity in star forming regions. Thus, understanding how its abundance evolves during the star formation process and whether it enriches the emerging planetary system is of paramount importance., [Methods] We used new data from the ALMA Large Program FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar protostars) to study the methanol line emission towards the [BHB2007] 11 protobinary system (sources A and B), where a complex structure of filaments connecting the two sources with a larger circumbinary disc has previously been detected., [Results] Twelve methanol lines have been detected with upper energies in the [45–537] K range along with one 13CH3OH transition and one methyl formate (CH3OCHO) line blended with one of the methanol transitions. The methanol emission is compact (FWHM ~ 0.5″) and encompasses both protostars, which are separated by only 0.2″ (28 au). In addition, the overall methanol line emission presents three velocity components, which are not spatially resolved by our observations. Nonetheless, a detailed analysis of the spatial origin of these three components suggests that they are associated with three different spatial regions, with two of them close to 11B and the third one associated with 11A. A radiative transfer analysis of the methanol lines gives a kinetic temperature of [100–140] K, an H2 volume density of 106–107 cm−3 and column density of a few 1018 cm−2 in all three components with a source size of ~0.15″. Thus, this hot and dense gas is highly enriched in methanol with an abundance as high as 10−5. Using previous continuum data, we show that dust opacity can potentially completely absorb the methanol line emission from the two binary objects., [Conclusions] Although we cannot firmly exclude other possibilities, we suggest that the detected hot methanol is resulting from the shocked gas from the incoming filaments streaming towards [BHB2007] 11A and B, respectively. Higher spatial resolution observations are necessary to confirm this hypothesis., This project has received funding within the European Union’s Horizon 2020 research and innovation program from the European Research Council (ERC) for the project The Dawn of Organic Chemistry (DOC), grant agreement no. 741002, and from the Marie Sklodowska-Curie for the project Astro-Chemical Origins (ACO), grant agreement no. 811312. I.J.-S. has received partial support from the Spanish State Research Agency (project number PID2019-105552RB-C41). D.J. is supported by NRC Canada and by an NSERC Discovery Grant. S.Y. thanks the support by Grant-in-Aids from Ministry of Education, Culture, Sports, Science, and Technologies of Japan (18H05222). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2018.1.01205.L. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST 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 National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

12 pags., 9 figs., 2 tabs., 3 apps., We report on the detection, for the first time in space, of the radical HCCCO and of pentacarbon monoxide, CO. The derived column densities are (1.6 ± 0.2) × 10cmand (1.5 ± 0.2) × 10cm, respectively. We have also analysed the data for all the molecular species of the families HCO and CnO within our QUIJOTE's line survey. Upper limits are obtained for HCO, HCO, CO, and CO. We report a robust detection of HCO and HCO based on 14 and 12 rotational lines detected with a signal-to-noise ratio ≥30 and ≥5, respectively. The derived N(HCO)/N(HCO) abundance ratio is 0.09 ± 0.03, while N(CO)/N(CO) is 80 ± 2, and N(HCO)/N(HCO) is 2.2 ± 0.3. As opposed to the cyanopolyyne family, HCN, which shows a continuous decrease in the abundances with increasing n, the CO and HCO species show a clear abundance maximum for n = 3 and 5, respectively. They also show an odd and even abundance alternation, with odd values of n being the most abundant, which is reminiscent of the behaviour of CH radicals, where in that case species with even values of n are more abundant. We explored the formation of these species through two mechanisms previously proposed, which are based on radiative associations between CHions with CO and reactions of Cand CHanions with O atoms, and we found that several species, such as CO, HCO, and HCO, are significantly overestimated. Our understanding of how these species are formed is incomplete as of yet. Other routes based on neutral-neutral reactions such as those of Cand CH carbon chains with O, OH, or HCO, could be behind the formation of these species., We thank Ministerio de Ciencia e Innovación of Spain (MICIU) for funding support through projects PID2019-106110GBI00, PID2019-107115GB-C21/AEI/10.13039/501100011033, and PID2019- 106235GB-I00. We also thank ERC for funding through grant ERC-2013-Syg 610256-NANOCOSMOS. M.A. thanks MICIU for grant RyC-2014-16277.

30 pags., 12 figs., 13 tabs., 4 apps., We report the detection of two isomers of ethynyl cyclopentadiene (c-C5H5CCH), namely 1- and 2-ethynyl-1,3-cyclopentadiene, in the direction of TMC-1. We derive column densities of (1.4 ± 0.2) × 1012 cm-2 and (2.0 ± 0.4) × 1012 cm-2, respectively, for these two cyclopentadiene derivatives, which imply that they are about ten times less abundant than cyclopentadiene. We also report the tentative detection of ethynyl benzene (C6H5CCH), for which we estimate a column density of (2.5 ± 0.4) × 1012 cm-2. We derived abundances for the corresponding cyano derivatives of cyclopentadiene and benzene and found values significantly lower than previously reported. The rotational temperature of the ethynyl and cyano derivatives of these cycles is about 9 K, that is, very close to the gas kinetic temperature of the cloud. The abundance ratio of the 1- and 2-isomers of ethynyl cyclopentadiene is 1.4 ± 0.5, while for the two isomers of cyano cyclopentadiene it is 2.4 ± 0.6. The relative abundances of CCH over CN derivatives is 7.7 ± 2.2 for cyclopentadiene, which probably reflects the abundance ratio of the radicals CCH and CN; this ratio is only 2.1 ± 0.5 for benzene, which suggests that additional reactions besides cyano radicals with benzene are involved in the formation of benzonitrile. The formation of these cycles is reasonably well accounted for through a chemical scheme based on neutral-neutral reactions. It is predicted that benzene should be as abundant as cyclopentadiene in TMC-1., We thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS and Ministerio de Ciencia e Innovación of Spain (MICIU) for funding support through projects PID2019-106110GB-I00, PID2019-107115GB-C21, and PID2019-106235GB-I00. M.A. thanks MICIU for grant RyC-2014-16277.

5 pags., 4 figs., We report the first detection in interstellar space of the 3-cyano propargyl radical (CH2C3N). This species was observed in the cold dark cloud TMC-1 using the Yebes 40m telescope. A total of seven rotational transitions for both ortho- and para-CH2C3N species were observed in the 31.0-50.4 GHz range. We derive a total column density of (1.6 ± 0.4) × 1011 cm-2 and an ortho/para ratio of 2.4 ± 1.2, which implies an abundance ratio CH2C3N/CH3C3N ∼0.1, in sharp contrast with the smaller analogues, in which case CH2CN/CH3CN ∼3. This indicates that the chemistry of the cyanides CH2C3N and CH3C3N behaves differently to that of the smaller analogues CH2CN and CH3CN. According to our chemical model calculations, the radical CH2C3N is mostly formed through the neutral-neutral reactions C + CH2CHCN, C2 + CH3CN, and CN + CH2CCH together with the dissociative recombination of the CH3C3NH+ ion with electrons. The neutral-neutral reaction N + C4H3 could also lead to CH2C3N, although its role is highly uncertain. The identified radical CH2C3N could play a role in the synthesis of large organic N-bearing molecules, such as benzonitrile (c-C6H5CN) or nitrogen heterocycles., This research has been funded by ERC through grant ERC-2013-Syg-610256-NANOCOSMOS. Authors also thank Ministerio de Ciencia e Innovación for funding support through projects PID2019-106235GBI00 and PID2019-107115GB-C21/AEI/10.13039/501100011033. M. A. thanks Ministerio de Ciencia e Innovación for grant RyC-2014-16277.

5 pags., 3 figs., 2 tabs., After the previous discovery of MgC3N and MgC4H in IRC +10216, a deeper Q-band (31.0-50.3 GHz) integration on this source had revealed two additional series of harmonically related doublets that we assigned on the basis of quantum mechanical calculations to the larger radicals MgC5N and MgC6H. The results presented here extend and confirm previous results on magnesium-bearing molecules in IRC +10216. We derived column densities of (4.7 ± 1.3) × 1012 for MgC5N and (2.0 ± 0.9) × 1013 for MgC6H, which imply that MgC5N/MgC3N = 0.5 and MgC6H/MgC4H = 0.9. Therefore, MgC5N and MgC6H are present with column densities not so different from those of the immediately shorter analogs. The synthesis of these large magnesium cyanides and acetylides in IRC +10216 can be explained for their shorter counterparts by a two-step process initiated by the radiative association of Mg+ with large cyanopolyynes and polyynes, which are still quite abundant in this source, followed by the dissociative recombination of the ionic complexes., We thank Ministerio de Ciencia e Innovación of Spain (MI-CIU) for funding support through projects AYA2016-75066- C2-1-P, PID2019-106110GB-I00, PID2019-107115GB-C21/AEI/10.13039/ 501100011033, and PID2019-106235GB-I00. We also thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS. M. A. thanks MICIU for grant RyC-2014-162

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, as part of ePESSTO/ePESSTO+ (the extended Public ESO Spectroscopic Survey for Transient Objects Survey). ePESSTO+ observations were obtained under ESO program ID 1103.D-0328 (PI: Inserra). EP would like to thank Stuart Sim for useful discussion on the working of TARDIS. This research made use of TARDIS, a community-developed software package for spectral synthesis in supernovae (Kerzendorf & Sim 2014; Kerzendorf et al. 2019). The development of TARDIS received support from the Google Summer of Code initiative and from the European Space Agency's (ESA) Summer of Code in Space program. TARDIS makes extensive use ofAstropy and PyNE. TWC acknowledges the funding provided by the Alexander von Humboldt Foundation and the EUFunding underMarie SklodowskaCurie grant H2020-MSCA-IF-2018-842471. TMBwas funded by the Comisi ' on Nacional de Investigaci ' on Cient ' ifica y Tecnol ' ogica (CONICYT) PFCHA/DOCTORADOBECAS CHILE/2017-72180113. MG is supported by the Polish Narodowe Centrum Nauki (NCN) MAESTRO grant 2014/14/A/ST9/00121. MN is supported by a Royal Astronomical Society Research Fellowship. ACK: LG was funded by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 839090. This work has been partially supported by the Spanish grant PGC2018-095317-B-C21 within the European Funds for Regional Development (FEDER). GL is supported by a research grant (19054) from VILLUM FONDEN This work makes use of observations from the Las Cumbres Observatory (LCO) global telescope network. The LCO team is supported by National Science Foundation (NSF) grants AST1911225, AST-1911151, and NASA grant 80NSSC19K1639. This paper is also based on observations made with Swift (UVOT) and the Liverpool Telescope (LT). The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de losMuchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council (STFC). LCO data have been obtained via Optical Infrared Co-ordination Network for Astronomy (OPTICON) proposals (IDs: SUPA2020B-002 OPTICON 20B/003 and SUPA2019B-007 OPTICON 19B-009). The OPTICON project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 730890. Thiswork hasmade use of data from the AsteroidTerrestrialimpact Last Alert System (ATLAS) project. The ATLAS project is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the Near-Earth Object (NEO) search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Minist ' erio da Ciencia, Tecnologia e Inovaces (MCTI/LNA) do Brasil, the US National Science Foundation`s NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU). This work has made use of data from the Gamma-ray Burst Optical/Near-infrared Detector (GROND) instrument at the 2.2 MPE telescope at La Silla, Chile. Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz-Prize to Prof. G. Hasinger (Deutsche Forschungsgemeinschaft (DFG) grant HA 1850/28-1). GROND data were obtained under European Southern Observatory (ESO) programme ID 0103.A-9099. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. This research made use of Photutils, an Astropy package for detection and photometry of astronomical sources (Bradley et al. 2020). Based on data products from observations made with ESO Telescopes at the La Silla or Paranal Observatories under ESO programme ID 179.A-2010. IRAF is distributed by the National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation. This research made use of NUMPY (Harris et al. 2020), MATPLOTLIB (Hunter 2007), and ASTROPY (Astropy Collaboration 2013, 2018)., We present optical spectroscopy together with ultraviolet, optical, and near-infrared photometry of SN 2019hcc, which resides in a host galaxy at redshift 0.044, displaying a sub-solar metallicity. The supernova spectrum near peak epoch shows a ‘w’ shape at around 4000 Å which is usually associated with OII lines and is typical of Type I superluminous supernovae. SN 2019hcc post-peak spectra show a well-developed Hα P-Cygni profile from 19 d past maximum and its light curve, in terms of its absolute peak luminosity and evolution, resembles that of a fast-declining Hydrogen-rich supernova (SN IIL). The object does not show any unambiguous sign of interaction as there is no evidence of narrow lines in the spectra or undulations in the light curve. Our TARDIS spectral modelling of the first spectrum shows that carbon, nitrogen, and oxygen (CNO) at 19 000 K reproduce the ‘w’ shape and suggests that a combination of non-thermally excited CNO and metal lines at 8000K could reproduce the feature seen at 4000 Å. The Bolometric light-curve modelling reveals that SN 2019hcc could be fit with a magnetar model, showing a relatively strong magnetic field (B > 3 × 1014 G), which matches the peak luminosity and rise time without powering up the light curve to superluminous luminosities. The high-energy photons produced by the magnetar would then be responsible for the detected OII lines. As a consequence, SN 2019hcc shows that a ‘w’ shape profile at around 4000 Å, usually attributed to OII, is not only shown in superluminous supernovae and hence it should not be treated as the sole evidence of the belonging to such a supernova type., European Organisation for Astronomical Research in the Southern Hemisphere, Chile, ePESSTO/ePESSTO+ extended Public ESO Spectroscopic Survey for Transient Objects Survey). ePESSTO+ observations were obtained under ESO program) 1103.D-0328, Google Incorporated, European Space Agency's (ESA) Summer of Code in Space program, Alexander von Humboldt Foundation, EU under Marie Sklodowska-Curie H2020-MSCA-IF-2018-842471, Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CHILE/2017-72180113, Polish Narodowe Centrum Nauki (NCN) MAESTRO grant 2014/14/A/ST9/00121, Royal Astronomical Society Research Fellowship, SKA South Africa 839090, European Commission PGC2018-095317-B-C21, VILLUM FONDEN 19054, National Science Foundation (NSF) AST-1911225 AST-1911151, National Aeronautics & Space Administration (NASA) 80NSSC19K1639 NN12AR55G 80NSSC18K0284 80NSSC18K1575, UK Research & Innovation (UKRI), Science & Technology Facilities Council (STFC), European Union's Horizon 2020 research and innovation programme 730890, Kepler/K2 grant J1944/80NSSC19K0112 HST GO-15889, Science & Technology Facilities Council (STFC) ST/T000198/1 ST/S006109/1, Gaia Multilateral Agreement, GROND, German Research Foundation (DFG) HA 1850/28-1, European Southern Observatory (ESO) programme 0103.A-9099, National Aeronautics & Space Administration (NASA), ESO Telescopes at the La Silla or Paranal Observatories under ESO programme 179.A-2010

24 pags., 11 figs., 2 tabs., High spectral resolution observations toward the low mass-loss rate C-rich, J-type asymptotic giant branch (AGB) star Y CVn were carried out at 7.5, 13.1, and 14.0 μm with the Echelon-cross-echelle Spectrograph mounted on the Stratospheric Observatory for Infrared Astronomy and the Texas Echelon-cross-echelle Spectrograph on the Infrared Telescope Facility. Around 130 HCN and H13CN lines of bands ν2, 2ν2, 2ν2 - ν2, 3ν2 - 2ν2, 3ν2 - ν2, and 4ν2 - 2ν2 were identified involving lower levels with energies up to ? 3900 K. These lines were complemented with the pure rotational lines J = 1-0 and 3-2 of the vibrational states up to 2ν2 acquired with the Institut de Radioastronomie Millimétrique 30 m telescope, and with the continuum taken with Infrared Space Observatory. We analyzed the data in detail by means of a ro-vibrational diagram and with a code written to model the absorption and emission of the circumstellar envelope of an AGB star. The continuum is mostly produced by the star with a small contribution from dust grains comprising warm to hot SiC and cold amorphous carbon. The HCN abundance distribution seems to be anisotropic close to Y CVn and in the outer layers of its envelope. The ejected gas is accelerated up to the terminal velocity (? 8 km s-1) from the photosphere to ? 3R? , but there is evidence of higher velocities (? 9-10 km s-1) beyond this region. In the vicinity of the star, the line widths are as high as ? 10 km s-1, which implies a maximum turbulent velocity of 6 km s-1 or the existence of other physical mechanisms probably related to matter ejection that involve higher gas expansion velocities than expected. HCN is rotationally and vibrationally out of local thermodynamic equilibrium throughout the whole envelope. It is surprising that a difference of about 1500 K in the rotational temperature at the photosphere is needed to explain the observations at 7.5 and 13-14 μm. Our analysis finds a total HCN column density that ranges from ? 2.1 × 1018 to 3.5 × 1018 cm-2, an abundance with respect to H2 of 3.5 × 10-5 to 1.3 × 10-4, and a 12C/13C isotopic ratio of ? 2.5 throughout the whole envelope., The research leading to these results has received funding support from the European Research Council under the European Union’s Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement n. 610256 NANOCOSMOS. EJM acknowledges financial support for this work through award #06_0144 which was issued by USRA and provided by NASA. MJR and EXES observations are supported by NASA cooperative agreement 80NSSC19K1701. MSG thanks Spanish MCIN through grant AYA2016-78994-P. Based in part on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NNA17BF53C, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration. This work is based on observations carried out under project numbers 155-16 and 048-17 with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This publication makes use of data products from the Widefield Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration

5 pags., 1 fig., 4 tabs., We report the first detection in space of the single deuterated isotopologue of methylcyanoacetylene, CH2DC3N. A total of 15 rotational transitions, with J = 8-12 and Ka = 0 and 1, were identified for this species in TMC-1 in the 31.0-50.4 GHz range using the Yebes 40 m radio telescope. The observed frequencies were used to derive for the first time the spectroscopic parameters of this deuterated isotopologue. We derive a column density of (8.0 ± 0.4)×1010 cm-2. The abundance ratio of CH3C3N to CH2DC3N is ∼22. We also theoretically computed the principal spectroscopic constants of 13C isotopologues of CH3C3N and CH3C4H and those of the deuterated isotopologues of CH3C4H for which we could expect a similar degree of deuteration enhancement. However, we have not detected either CH2DC4H or CH3C4D, nor any 13C isotopologues. The different observed deuterium ratios in TMC-1 are reasonably accounted for by a gas-phase chemical model where the low temperature conditions favour deuteron transfer through reactions with H2D+., We thank ERC for funding through grant ERC2013-Syg-610256-NANOCOSMOS. The Spanish authors thank Ministerio de Ciencia e Innovación for funding support through project AYA2016-75066-C2-1-P, PID2019-106235GB-I00 and PID2019-107115GBC21/AEI/10.13039/501100011033. MA thanks Ministerio de Ciencia e Innovación for grant RyC-2014-16277. ER acknowledges the support of the Programme National ‘Physique et Chimie du Milieu Interstellaire’ (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES.

12 pags., 7 figs., 3 tabs., We report the detection for the first time in space of three new pure hydrocarbon cycles in TMC-1: c-C3HCCH (ethynyl cyclopropenylidene), c-C5H6 (cyclopentadiene), and c-C9H8 (indene). We derive a column density of 3.1 × 1011 cm-2 for the first cycle and similar values, in the range (1-2) × 1013 cm-2, for the second and third. This means that cyclopentadiene and indene, in spite of their large size, are exceptionally abundant, only a factor of five less abundant than the ubiquitous cyclic hydrocarbon c-C3H2. The high abundance found for these two hydrocarbon cycles together with the high abundance previously found for the propargyl radical (CH2CCH) and other hydrocarbons, such as vinyl and allenyl acetylene (Agúndez et al. 2021, A&A, 647, L10; Cernicharo et al. 2021a, A&A, 647, L2; Cernicharo et al. 2021b, A&A, 647, L3), start to allow us to quantify the abundant content of hydrocarbon rings in cold dark clouds and to identify the intermediate species that are probably behind the in situ bottom-up synthesis of aromatic cycles in these environments. While c-C3HCCH is most likely formed through the reaction between the radical CCH and c-C3H2, the high observed abundances of cyclopentadiene and indene are difficult to explain through currently proposed chemical mechanisms. Further studies are needed to identify how five- and six-membered rings are formed under the cold conditions of a cloud such as TMC-1., We thank ERC for funding through grant ERC2013-Syg-610256-NANOCOSMOS. We also thank Ministerio de Ciencia e Innovación of Spain (MICIU) for funding support through projects AYA2016-75066-C2-1-P, PID2019-106110GB-I00, PID2019-107115GBC21/AEI/10.13039/501100011033, and PID2019-106235GB-I00. M.A. thanks MICIU for grant RyC-2014-16277.

6 pags., 4 figs., 1 tab., We report the detection of the oxygen-bearing complex organic molecules propenal (C2H3CHO), vinyl alcohol (C2H3OH), methyl formate (HCOOCH3), and dimethyl ether (CH3OCH3) toward the cyanopolyyne peak of the starless core TMC-1. These molecules were detected through several emission lines in a deep Q-band line survey of TMC-1 carried out with the Yebes 40m telescope. These observations reveal that the cyanopolyyne peak of TMC-1, which is a prototype of a cold dark cloud rich in carbon chains, also contains O-bearing complex organic molecules such as HCOOCH3 and CH3OCH3, which have previously been seen in a handful of cold interstellar clouds. In addition, this is the first secure detection of C2H3OH in space and the first time that C2H3CHO and C2H3OH have been detected in a cold environment, adding new pieces to the puzzle of complex organic molecules in cold sources. We derive column densities of (2.2 ± 0.3) × 1011 cm-2, (2.5 ± 0.5) × 1012 cm-2, (1.1 ± 0.2) × 1012 cm-2, and (2.5 ± 0.7) × 1012 cm-2 for C2H3CHO, C2H3OH, HCOOCH3, and CH3OCH3, respectively. Interestingly, C2H3OH has an abundance similar to that of its well-known isomer acetaldehyde (CH3CHO), with C2H3OH/CH3CHO ∼1 at the cyanopolyyne peak. We discuss potential formation routes to these molecules and recognize that further experimental, theoretical, and astronomical studies are needed to elucidate the true formation mechanism of these O-bearing complex organic molecules in cold interstellar sources., We acknowledge funding support from Spanish MICIU through grants AYA2016-75066-C2-1-P, PID2019-106110GB-I00, PID2019- 106235GB-I00, and PID2019-107115GB-C21 and from the European Research Council (ERC Grant 610256: NANOCOSMOS). M. A. also acknowledges funding support from the Ramón y Cajal programme of Spanish MICIU (grant RyC2014-16277).

8 pags., 3 figs., 3 tabs., Three compounds with a CHO formula have been detected in the Interstellar Medium (ISM): ethyl formate (CHCHOC(O)H), methyl acetate (CHOC(O)CH) and very recently hydroxyacetone (CHC(O)CHOH). The higher thermodynamic stability of another isomer, the propanoic acid (CHCHC(O)OH), clearly suggests that this molecule should be considered as a possible candidate for ISM detection. To provide reliable predictions for astronomical use in the millimeter and submillimeter wave ranges we performed a new study of propanoic acid rotational spectrum up to 545 GHz. The analysis of large amplitude methyl top torsional motion in this molecule was carried out using the rho axis method and the RAM36 program code. More than 3200 lines corresponding to the rotational transitions in the ground and first excited methyl top torsional states were newly assigned and fit within experimental error. This enabled us to produce new predictions which were used to search for propanoic acid in two high-mass star-forming regions: SgrB2 (public IRAM 30 m) and Orion KL (ALMA Science Verification). We report a non-detection of propanoic acid in these clouds and derive upper limits to the column density., LM/RAM/JCG acknowledge the support of the Programme National “Physique et Chimie du Milieu Interstellaire” (PCMI) of CNRS/INSU. JCG thanks also the Centre National d’Etudes Spatiales (CNES) for a grant. BT and JC thank Ministerio de Ciencia e Innovaci ́on of Spain (MICIU) for funding support through projects AYA2016-75066-C2-1-P, PID2019-106110 GB-I00, PID2019-107115 GB-C21/ AEI/ 10.13039/ 501100011033, and PID2019-106235 GB-I00. We also thank ERC for funding through grant ERC2013-Syg-610256-NANOCOSMOS. This paper makes use of the following ALMA data: ADS/JAO. ALMA⧹♯2011.0.00009.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan) 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. This work was also based on observations carried out with the IRAM 30-meter telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain)

7 pags., 2 figs., 7 tabs., We report the first detection in space of the two doubly deuterated isotopologues of methyl acetylene. The species CHD2CCH and CH2DCCD were identified in the dense core L483 through, respectively, nine and eight rotational lines in the 72-116 GHz range using the 30 m telescope of the Institut de Radioastronomie Millimétrique (IRAM). We combined the astronomical frequencies observed here with laboratory frequencies from the literature measured in the 29-47 GHz range to derive more accurate spectroscopic parameters for the two isotopologues. We derive beam-averaged column densities of (2.7 ± 0.5) × 1012 cm-2 for CHD2CCH and (2.2 ± 0.4) × 1012 cm-2 for CH2DCCD, which translate to abundance ratios of CH3CCH/CHD2CCH = 34 ± 10 and CH3CCH/CH2DCCD = 42 ± 13. The doubly deuterated isotopologues of methyl acetylene are only a few times less abundant than the singly deuterated ones, specifically around 2.4 times less abundant than CH3CCD. The abundances of the different deuterated isotopologues with respect to CH3CCH are reasonably accounted for by a gas-phase chemical model in which deuteration occurs from the precursor ions C3H6D+ and C3H5D+, when the ortho-to-para ratio of molecular hydrogen is sufficiently low. This points to gas-phase chemical reactions, rather than grain-surface processes, as being responsible for the formation and deuterium fractionation of CH3CCH in L483. The abundance ratios CH2DCCH/CH3CCD = 3.0 ± 0.9 and CHD2CCH/CH2DCCD = 1.25 ± 0.37 observed in L483 are consistent with the statistically expected values of three and one, respectively, with the slight overabundance of CHD2CCH compared to CH2DCCD being well explained by the chemical model., We acknowledge funding support from Spanish MICIU through grants AYA2016-75066-C2-1-P, PID2019-106110GB-I00, and PID2019-107115GB-C21 and from the European Research Council (ERC Grant 610256: NANOCOSMOS). M.A. also acknowledges funding support from the Ramón y Cajal programme of Spanish MICIU (grant RyC-2014-16277).

10 pags., 7 figs., 2 tabs., We present Yebes 40 m telescope observations of the three most stable C4H3N isomers towards the cyanopolyyne peak of TMC-1. We have detected 13 transitions from CH3C3N (A and E species), 16 lines from CH2CCHCN, and 27 lines (a-Type and b-Type) from HCCCH2CN. We thus provide a robust confirmation of the detection of HCCCH2CN and CH2CCHCN in space. We have constructed rotational diagrams for the three species and obtained rotational temperatures between 4 and 8 K as well as similar column densities for the three isomers, in the range (1.5-3)â ×â 1012 cm-2. Our chemical model provides abundances of the order of the observed ones, although it overestimates the abundance of CH3CCCN and underestimates that of HCCCH2CN. The similarity of the observed abundances of the three isomers suggests a common origin, most probably involving reactions of the radical CN with the unsaturated hydrocarbons methyl acetylene and allene. Studies of reaction kinetics at low temperatures and further observations of these molecules in different astronomical sources are needed to draw a clear picture of the chemistry of C4H3N isomers in space., We acknowledge funding support from the European Research Council (ERC Grant 610256: NANOCOSMOS). We also thank the Spanish MICIU for funding support under grants AYA2016-75066-C2-1-P, PID2019-106110GB-I00, PID2019-107115GB-C21, and PID2019-106235GBI00. M.A. thanks MICIU for grant RyC-2014-16277.

12 pags., 6 figs., 7 tabs., Using the Yebes 40 m and IRAM 30 m radiotelescopes, we detected two series of harmonically related lines in space that can be fitted to a symmetric rotor. The lines have been seen towards the cold dense cores TMC-1, L483, L1527, and L1544. High level of theory ab initio calculations indicate that the best possible candidate is the acetyl cation, CH3CO+, which is the most stable product resulting from the protonation of ketene. We have produced this species in the laboratory and observed its rotational transitions Ju = 10 up to Ju = 27. Hence, we report the discovery of CH3CO+ in space based on our observations, theoretical calculations, and laboratory experiments. The derived rotational and distortion constants allow us to predict the spectrum of CH3CO+ with high accuracy up to 500 GHz. We derive an abundance ratio N(H2CCO)/N(CH3CO+) ∼44. The high abundance of the protonated form of H2CCO is due to the high proton affinity of the neutral species. The other isomer, H2CCOH+, is found to be 178.9 kJ mol-1 above CH3CO+. The observed intensity ratio between the K = 0 and K = 1 lines, ∼2.2, strongly suggests that the A and E symmetry states have suffered interconversion processes due to collisions with H and/or H2, or during their formation through the reaction of H3+ with H2CCO., The Spanish authors thank Ministerio de Ciencia e Innovación for funding support through project AYA2016-75066-C2-1-P, PID2019- 106235GB-I00 and PID2019-107115GB-C21/AEI/10.13039/501100011033. We also thank ERC for funding through grant ERC-2013-Syg-610256- NANOCOSMOS. MA and CB thanks Ministerio de Ciencia e Innovación for grants RyC-2014-16277 and FJCI-2016-27983, respectively. Y. Endo thanks Ministry of Science and Technology of Taiwan through grant MOST108-2113- M-009-25.

25 pags., 24 figs., 9 tabs., Hydride molecules lie at the base of interstellar chemistry, but the synthesis of sulfuretted hydrides is poorly understood and their abundances often crudely constrained. Motivated by new observations of the Orion Bar photodissociation region (PDR) - 100 resolution ALMA images of SH+; IRAM 30 m detections of bright H32 2 S, H34 2 S, and H33 2 S lines; H3S+ (upper limits); and SOFIA/GREAT observations of SH (upper limits) we perform a systematic study of the chemistry of sulfur-bearing hydrides. We self-consistently determine their column densities using coupled excitation, radiative transfer as well as chemical formation and destruction models. We revise some of the key gas-phase reactions that lead to their chemical synthesis. This includes ab initio quantum calculations of the vibrational-state-dependent reactions SH+ + H2(v) H2S+ + H and S + H2 (v) SH + H.We find that reactions of UV-pumped H2(v 2) molecules with S+ ions explain the presence of SH+ in a high thermal-pressure gas component, Pth=k 108 cm-3 K, close to the H2 dissociation front (at AV < 2 mag). These PDR layers are characterized by no or very little depletion of elemental sulfur from the gas. However, subsequent hydrogen abstraction reactions of SH+, H2S+, and S atoms with vibrationally excited H2, fail to form enough H2S+, H3S+, and SH to ultimately explain the observed H2S column density (∼2.5 1014 cm-2, with an ortho-to-para ratio of 2.9 .3; consistent with the high-temperature statistical value). To overcome these bottlenecks, we build PDR models that include a simple network of grain surface reactions leading to the formation of solid H2S (s-H2S). The higher adsorption binding energies of S and SH suggested by recent studies imply that S atoms adsorb on grains (and form s-H2S) at warmer dust temperatures (Td < 50 K) and closer to the UV-illuminated edges of molecular clouds. We show that everywhere s-H2S mantles form(ed), gas-phase H2S emission lines will be detectable. Photodesorption and, to a lesser extent, chemical desorption, produce roughly the same H2S column density (a few 1014 cm-2) and abundance peak (a few 10-8) nearly independently of nH and G0. This agrees with the observed H2S column density in the Orion Bar as well as at the edges of dark clouds without invoking substantial depletion of elemental sulfur abundances., We thank the Spanish MICIU for funding support under grants AYA2016-75066-C2-2-P, AYA2017-85111-P, FIS2017-83473-C2 PID2019-106110GB-I00, and PID2019-106235GB-I00 and the French-Spanish collaborative project PICS (PIC2017FR). We finally acknowledge computing time at Finisterrae (CESGA) under RES grant ACCT-2019-3-0004.

11 pags., 8 figs., 1 tab., We present the discovery in TMC-1 of vinyl acetylene, CHCHCCH, and the detection, for the first time in a cold dark cloud, of HCCN, HC N, and CH CHCN. A tentative detection of CH CHCCH is also reported. The column density of vinyl acetylene is (1.2 ± 0.2) × 10 cm, which makes it one of the most abundant closed-shell hydrocarbons detected in TMC-1. Its abundance is only three times lower than that of propylene, CH CHCH. The column densities derived for HCCN and HC N are (4.4 ± 04) × 10 cm and (3.7 ± 0.4) × 10 cm, respectively. Hence, the HCCN/HC N abundance ratio is 1.2 ± 0.3. For ethyl cyanide we derive a column density of (1.1 ± 0.3) × 10 cm. These results are compared with a state-of-the-art chemical model of TMC-1, which is able to account for the observed abundances of these molecules through gas-phase chemical routes., We thank Ministerio de Ciencia e Innovación of Spain (MICIU) for funding support through projects AYA2016-75066-C2-1-P, PID 2019-106110GB-I00, PID2019-107115GB-C21/AEI/10.13039/501100011033, and PID2019-106235GB-I00. We also thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS. M.A. thanks MICIU for grant RyC2014-16277.

7 pags., 3 figs., 3 tabs., We present the discovery in TMC-1 of allenyl acetylene, H2CCCHCCH, through the observation of nineteen lines with a signal-to-noise ratio ∼4-15. For this species, we derived a rotational temperature of 7 1 K and a column density of 1.2 0.2 × 1013 cm-2. The other well known isomer of this molecule, methyl diacetylene (CH3C4H), has also been observed and we derived a similar rotational temperature, Tr = 7.0 0.3 K, and a column density for its two states (A and E) of 6.5 0.3 × 1012 cm-2. Hence, allenyl acetylene and methyl diacetylene have a similar abundance. Remarkably, their abundances are close to that of vinyl acetylene (CH2CHCCH). We also searched for the other isomer of C5H4, HCCCH2CCH (1.4-Pentadiyne), but only a 3 upper limit of 2.5 × 1012 cm-2 to the column density can be established. These results have been compared to state-of-the-art chemical models for TMC-1, indicating the important role of these hydrocarbons in its chemistry. The rotational parameters of allenyl acetylene have been improved by fitting the existing laboratory data together with the frequencies of the transitions observed in TMC-1., We thank Ministerio de Ciencia e Innovación of Spain (MICIU) for funding support through projects AYA2016-75066-C2-1-P, PID2019-106110GB-I00, PID2019-107115GBC21/AEI/10.13039/501100011033, and PID2019-106235GB-I00. We also thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS. M.A. thanks MICIU for grant RyC-2014-16277.

5 pags., 5 figs., 2 tabs., We report the first detection in space of the cumulene carbon chain l-H2C5. A total of eleven rotational transitions, with Jup = 7-10 and Ka = 0 and 1, were detected in TMC-1 in the 31.0-50.4 GHz range using the Yebes 40 m radio telescope. We derived a column density of (1.8 ± 0.5) × 1010 cm-2. In addition, we report observations of other cumulene carbenes detected previously in TMC-1 in order to compare their abundances with the newly detected cumulene carbene chain. We find that l-H2C5 is ∼4.0 times less abundant than the larger cumulene carbene l-H2C6, while it is ∼300 and ∼500 times less abundant than the shorter chains l-H2C3 and l-H2C4. We discuss the most likely gas-phase chemical routes to these cumulenes in TMC-1 and stress that chemical kinetics studies able to distinguish between different isomers are needed to shed light on the chemistry of CnH2 isomers with n > 3., This research has been funded by ERC through grant ERC-2013-Syg-610256-NANOCOSMOS. Authors also thank Ministerio de Ciencia e Innovación for funding support through projects AYA2016-75066-C2-1-P, PID2019-106235GB-I00 and PID2019-107115GBC21/AEI/10.13039/501100011033. MA thanks Ministerio de Ciencia e Innovación for grant RyC-2014-16277.

Martín, S., et al., [Context] The interstellar medium is the locus of physical processes affecting the evolution of galaxies which drive or are the result of star formation activity, supermassive black hole growth, and feedback. The resulting physical conditions determine the observable chemical abundances that can be explored through molecular emission observations at millimeter and submillimeter wavelengths. [Aims] Our goal is to unveiling the molecular richness of the central region of the prototypical nearby starburst galaxy NGC 253 at an unprecedented combination of sensitivity, spatial resolution, and frequency coverage. [Methods] We used the Atacama Large Millimeter/submillimeter Array (ALMA), covering a nearly contiguous 289 GHz frequency range between 84.2 and 373.2 GHz, to image the continuum and spectral line emission at 1.6″(∼28 pc) resolution down to a sensitivity of 30 - 50 mK. This article describes the ALMA Comprehensive High-resolution Extragalactic Molecular Inventory (ALCHEMI) large program. We focus on the analysis of the spectra extracted from the 15″ (∼255 pc) resolution ALMA Compact Array data. [Results] We modeled the molecular emission assuming local thermodynamic equilibrium with 78 species being detected. Additionally, multiple hydrogen and helium recombination lines are identified. Spectral lines contribute 5 to 36% of the total emission in frequency bins of 50 GHz. We report the first extragalactic detections of C2H5OH, HOCN, HC3HO, and several rare isotopologues. Isotopic ratios of carbon, oxygen, sulfur, nitrogen, and silicon were measured with multiple species. [Concluison] Infrared pumped vibrationaly excited HCN, HNC, and HC3N emission, originating in massive star formation locations, is clearly detected at low resolution, while we do not detect it for HCO+. We suggest high temperature conditions in these regions driving a seemingly "carbon-rich"chemistry which may also explain the observed high abundance of organic species close to those in Galactic hot cores. The Lvib/LIR ratio was used as a proxy to estimate a 3% contribution from the proto super star cluster to the global infrared emission. Measured isotopic ratios with high dipole moment species agree with those within the central kiloparsec of the Galaxy, while those derived from 13C/18O are a factor of five larger, confirming the existence of multiple interstellar medium components within NGC 253 with different degrees of nucleosynthesis enrichment. The ALCHEMI data set provides a unique template for studies of star-forming galaxies in the early Universe.

8 pags., 5 figs., 2 tabs., The abundances of chemical elements and their depletion factors are essential parameters for understanding the composition of the gas and dust that are ultimately incorporated into stars and planets. Sulfur is an abundant but peculiar element in the sense that, despite being less volatile than other elements (e.g., carbon), it is not a major constituent of dust grains in diffuse interstellar clouds. Here, we determine the gas-phase carbon-to-sulfur abundance ratio, [C]/[S], and the [S] in a dense star-forming cloud from new radio recombination lines (RRLs) detected with the Yebes 40m telescope-at relatively high frequencies (∼40 GHz ∼7 mm) and angular resolutions (down to 36″)-in the Orion Bar, a rim of the Orion Molecular Cloud (OMC). We detect nine Cnα RRLs (with n = 51-59) as well as nine narrow line features separated from the Cnα lines by δv =-8.4 ± 0.3 km s-1. Based on this velocity separation, we assign these features to sulfur RRLs, with little contribution of RRLs from the more condensable elements Mg, Si, or Fe. Sulfur RRLs lines trace the photodissociation region of the OMC. In these neutral gas layers, up to AV ∼4, the ions C+ and S+ lock in most of the C and S gas-phase reservoir. We determine a relative abundance of [C]Ori/[S]Ori = 10.4 ± 0.6 and, adopting the same [C]Ori measured in the translucent gas toward star θ1 Ori B, an absolute abundance of [S]Ori = (1.4 ± 0.4) 10-5. This value is consistent with emission models of the observed sulfur RRLs if N(S+) ∼7 1017 cm-2 (beam-averaged). The [S]Ori is the "initial"sulfur abundance in the OMC, before an undetermined fraction of the [S]Ori goes into molecules and ice mantles in the cloud interior. The inferred abundance [S]Ori matches the solar abundance, thus implying that there is little depletion of sulfur onto rocky dust grains, with D(S) = 0.0 ± 0.2 dex., We thank the Spanish MCIYU for funding support under grants PID2019-106110GB-I00 and AYA2016-75066-C2-1-P.

7 pags., 3 figs., 1 tab. We report the detection, for the first time in space, of a new non-functionalised hydrocarbon cycle in the direction of TMC-1: o-C6H4 (ortho-benzyne). We derive a column density for this hydrocarbon cycle of (5.0 ± 1.0) × 1011 cm-2. The abundance of this species is around 30 times lower than that of cyclopentadiene and indene. We compare the abundance of benzyne with that of other pure hydrocarbons, cycles or chains, and find that it could be formed from neutral-radical reactions such as C2H + CH2CHCCH and C + C5H5, and possibly through C4H + C2H4, C3H + CH2CCH2, and C3H2 + C3H3. Hence, the rich content of hydrocarbon cycles observed in TMC-1 could arise through a bottom-up scenario involving reactions of a few radicals with the abundant hydrocarbons recently revealed by the QUIJOTE line survey. We thank ERC for funding through grant ERC-2013-Syg610256-NANOCOSMOS. M.A. thanks MICIU for grant RyC-2014-16277. We also thank Ministerio de Ciencia e Innovación of Spain (MICIU) for funding support through projects AYA2016-75066-C2-1-P, PID2019-106110GB-I00, PID2019-107115GB-C21/AEI/10.13039/501100011033, and PID2019-10623 5GB-I00

9 pags., 5 figs., 5 tabs., We report the first identification in space of H2NC, a high-energy isomer of H2CN that has been largely ignored in chemical and astrochemical studies. The observation of various unidentified lines around 72.2 GHz in the cold dark cloud L483 motivated the search and successful detection of additional groups of lines in harmonic relation. Following an exhaustive high-level ab initio screening of possible carriers, we confidently assign the unidentified lines to H2NC based on the good agreement between the astronomical and theoretical spectroscopic parameters alongside sound spectroscopic and astrochemical arguments. The observed frequencies are used to precisely characterize the rotational spectrum of H2NC. This species is also detected in the cold dark cloud B1-b and the z = 0.89 galaxy in front of the quasar PKS 1830-211. We derive H2NC/H2CN abundance ratios ∼1 in L483 and B1-b and 0.27 toward PKS 1830-211. Neither H2NC nor H2CN are detected in the dark cloud TMC-1, which seriously undermines the previous identification of H2CN in this source. We suggest that the H2NC/H2CN ratio behaves as the HNC/HCN ratio, with values close to one in cold dense clouds and below one in diffuse clouds. The reactions N + CH3 and C + NH3 emerge as strong candidates for the production of H2NC in interstellar clouds. Further studies on these two reactions are needed to evaluate the yield of H2NC. Due to the small number of atoms involved, it should be feasible to constrain the chemistry behind H2NC and H2CN, just as has been done for HNC and HCN, as this could allow for the H2NC/H2CN ratio to be applied as a probe of chemical or physical conditions of the host clouds., We acknowledge funding support from Spanish Ministerio de Ciencia e Innovación through grants AYA2016-75066-C2-1-P, PID2019-106110GB-I00, and PID2019-107115GB-C21, and from the European Research Council (ERC Grant 610256: NANOCOSMOS). M.A. also acknowledges funding support from the Ramón y Cajal programme of Spanish Ministerio de Ciencia e Innovación (grant RyC-2014-16277).

We examine four high resolution reflection grating spectrometers (RGS) spectra of the February 2009 outburst of the luminous recurrent nova LMC 2009a. They were very complex and rich in intricate absorption and emission features. The continuum was consistent with a dominant component originating in the atmosphere of a shell burning white dwarf (WD) with peak effective temperature between 810,000 K and a million K, and mass in the 1.2-1.4 M$_\odot$ range. A moderate blue shift of the absorption features of a few hundred km s$^{-1}$ can be explained with a residual nova wind depleting the WD surface at a rate of about 10$^{-8}$ M$_\odot$ yr$^{-1}$. The emission spectrum seems to be due to both photoionization and shock ionization in the ejecta. The supersoft X-ray flux was irregularly variable on time scales of hours, with decreasing amplitude of the variability. We find that both the period and the amplitude of another, already known 33.3 s modulation, varied within timescales of hours. We compared N LMC 2009a with other Magellanic Clouds novae, including 4 serendipitously discovered as supersoft X-ray sources (SSS) among 13 observed within 16 years after the eruption. The new detected targets were much less luminous than expected: we suggest that they were partially obscured by the accretion disk. Lack of SSS detections in the Magellanic Clouds novae more than 5.5 years after the eruption constrains the average duration of the nuclear burning phase., Comment: Accepted for publication in MNRAS

6 pags., 2 figs., 2 tabs., We present the first identification in interstellar space of the propargyl radical (CH2CCH). This species was observed in the cold dark cloud TMC-1 using the Yebes 40 m telescope. The six strongest hyperfine components of the 20,2-10,1 rotational transition, lying at 37.46 GHz, were detected with signal-to-noise ratios from 4.6σ to 12.3σ. We derived a column density of 8.7 × 1013 cm-2 for CH2CCH, which translates to a fractional abundance relative to H2 of 8.7 × 10-9. This radical has a similar abundance as methyl acetylene, with an abundance ratio CH2CCH/CH3CCH close to one. The propargyl radical is thus one of the most abundant radicals detected in TMC-1, and it is probably the most abundant organic radical with a certain chemical complexity ever found in a cold dark cloud. We constructed a gas-phase chemical model and find calculated abundances that agree with, or fall two orders of magnitude below, the observed value depending on the poorly constrained low-temperature reactivity of CH2CCH with neutral atoms. According to the chemical model, the propargyl radical is essentially formed by the C + C2H4 reaction and by the dissociative recombination of C3$ \rm{H}n $ ions with n = 4-6. The propargyl radical is believed to control the synthesis of the first aromatic ring in combustion processes, and it probably plays a key role in the synthesis of large organic molecules and cyclization processes to benzene in cold dark clouds., We acknowledge funding support from Spanish MICIU through grants AYA2016-75066-C2-1-P, PID2019-106110GB-I00, and PID2019-107115GBC21 and from the European Research Council (ERC Grant 610256: NANOCOSMOS). M.A. also acknowledges funding support from the Ramón y Cajal programme of Spanish MICIU (grant RyC-2014-16277).

9 pags., 3 figs., 6 tabs., Context. S-methyl thioformate CH3SC(O)H is a monosulfur derivative of methyl formate, a relatively abundant component of the interstellar medium (ISM). S-methyl thioformate being, thermodynamically, the most stable isomer, it can be reasonably proposed for detection in the ISM. Aims. This work aims to experimentally study and theoretically analyze the ground and first torsional excited states for CH3SC(O)H in a large spectral range for astrophysical use. Methods. S-methyl thioformate was synthesized as a result of a reaction of methyl mercaptan with acetic-formic anhydride. The millimeter-wave spectrum was then recorded for the first time from 150 to 660 GHz with the solid-state spectrometer located at Lille. Results. A set of 3545 lines is determined and combined with 54 previously measured lines in the microwave region, belonging to ground state νt = 0 as well as 1391 transitions in the first excited state of torsion ν18 = 1. Some 164 lines were also assigned to ν18 = 2 for the A-species. A global fit was performed using the BELGI-Cs code taking into account the large splitting of A and E lines due to methyl internal rotation motion with a relatively low barrier, V3 = 127.4846(15) cm-1. Conclusions. Using our spectroscopy work, a deep search of S-methyl thioformate was carried out in the IRAM 30 m and ALMA data of different high-mass star-forming regions (Orion KL and Sgr B2). We derived an upper limit to the CH3SC(O)H column density in these regions., This paper makes use of the following ALMA data: ADS/JAO.ALMA #2011.0.00009.SV. 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 results are also based on observations obtained with the IRAM 30 m telescope supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). This work was supported by the Programme National Physique et Chimie du Milieu Intestellaire (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES. B.T. and J.C. thank the ERC for support under grant ERC-2013-Syg-610 256- NANOCOSMOS and the Spanish MINECO for funding support under grants AYA2012-32032 and FIS2014-52172-C2, and the CONSOLIDER-Ingenio program “ASTROMOL” CSD 2009-00038. J.-C.G. thanks the Centre National d’Etudes Spatiales (CNES) for a grant.

22 pags., 27 figs., 6 tabs., Context. Yebes 40 m radio telescope is the main and largest observing instrument at Yebes Observatory and is devoted to very long baseline interferometry (VLBI) and single-dish observations since 2010. It has been covering frequency bands between 2 GHz and 90 GHz in discontinuous and narrow windows in most cases in order to match the current needs of the European VLBI Network (EVN) and the Global Millimeter VLBI Array (GMVA). Aims. The Nanocosmos project, a European Union-funded synergy grant, has enabled an increase in the instantaneous frequency coverage of the Yebes 40 m radio telescope, making it possible to observe many molecular transitions with single tunings in single-dish mode. This reduces the observing time and maximises the output from the telescope. Methods. We present technical specifications of the recently installed 31.5-50 GHz (Q band) and 72-90.5 GHz (W band) receivers along with the main characteristics of the telescope at these frequency ranges. We observed IRC+10216, CRL 2688, and CRL 618, which harbour a rich molecular chemistry, to demonstrate the capabilities of the new instrumentation for spectral observations in single-dish mode. Results. Our results show the high sensitivity of the telescope in the Q band. The spectrum of IRC+10126 offers an unprecedented signal-to-noise ratio for this source in this band. On the other hand, the spectrum normalised by the continuum flux towards CRL 618 in the W band demonstrates that the 40 m radio telescope produces comparable results to those from the IRAM 30 m radio telescope, although with a lower sensitivity. The new receivers fulfil one of the main goals of Nanocosmos and open up the possibility to study the spectrum of different astrophysical media with unprecedented sensitivity., The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC-SyG-2013 Grant Agreement No. 610256 Nanocosmos. Part of this work was supported by Programa operativo pluriregional de España, YDALGO. The observations mentioned in this article have been done under commissioning time and within projects 19A010 and 20A017. The Yebes 40m radio telescope belongs to Instituto Geográfico Nacional (IGN).

9 pags., 4 figs., 9 tabs., Using the Yebes 40m radio telescope, we report the detection of a series of seven lines harmonically related with a rotational constant B0 = 1295.81581 ± 0.00026MHz and a distortion constant D0 = 27.3 ± 0.5Hz towards the cold dense cloud TMC-1. Ab initio calculations indicate that the best possible candidates are the cations HC5NH+ and NC4NH+. From a comparison between calculated and observed rotational constants and other arguments based on proton affinities and dipole moments, we conclude that the best candidate for a carrier of the observed lines is the protonated cyanodiacetylene cation, HC5NH+. The HC5N/HC5NH+ ratio derived in TMC-1 is 240, which is very similar to the HC3N/HC3NH+ ratio. Results are discussed in the framework of a chemical model for protonated molecules in cold dense clouds., The Spanish authors thank Ministerio de Ciencia e Innovación for funding support through project AYA2016-75066-C2-1-P. We also thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS. M.A. thanks Ministerio de Ciencia e Innovación for Ramón y Cajal Grant RyC2014-16277.

11 pags., 7 figs., 8 tabs., We present a study of the isocyano isomers of the cyanopolyynes HC3N, HC5N, and HC7N in TMC-1 and IRC+10216 carried out with the Yebes 40m radio telescope. This study has enabled us to report the detection, for the first time in space, of HCCCCNC in TMC-1 and to give upper limits for HC6NC in the same source. In addition, the deuterated isotopologues of HCCNC and HNCCC were detected, along with all 13C substitutions of HCCNC, also for the first time in space. The abundance ratios of HC3N and HC5N, with their isomers, are very different in TMC-1 and IRC+10216, namely, N(HC5N)/N(HC4NC) is ∼300 and ≥2100, respectively. We discuss the chemistry of the metastable isomers of cyanopolyynes in terms of the most likely formation pathways and by comparing observational abundance ratios between different sources., The Spanish authors thank Ministerio de Ciencia e Innovación for funding support through project AYA2016-75066-C2-1-P. We also thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS. MA and CB thanks Ministerio de Ciencia e Innovación for Ramón y Cajal grant RyC-2014-16277 and Juan de la Cierva grant FJCI-2016-27983.

12 pags., 8 figs., 8 tabs.-- Section: Letters to the Editor, Observations of IRC +10216 with the Yebes 40 m telescope between 31 and 50 GHz have revealed more than 150 unidentified lines. Some of them can be grouped into a new series of 26 doublets, harmonically related with integer quantum numbers ranging from Jup = 54 to 80. The separation of the doublets increases systematically with J, that is to say, as expected for a linear species in one of its bending modes. The rotational parameters resulting from the fit to these data are B = 290.8844 ± 0.0004 MHz, D = 0.88 ± 0.04 Hz, and q = 0.1463 ± 0.0001 MHz. The rotational constant is very close to that of the ground state of HC9N. Our ab initio calculations show an excellent agreement between these parameters and those predicted for the lowest energy vibrationally excited state, ν19 = 1, of HC9N. This is the first detection, and complete characterization in space, of vibrationally excited HC9N. An energy of 41.5 cm-1 is estimated for the ν19 state. In addition, 17 doublets of HC7N in the ν15 = 1 state, for which laboratory spectroscopy is available, were detected for the first time in IRC +10216. Several doublets of HC5N in its ν11 = 1 state were also observed. The column density ratio between the ground and the lowest excited vibrational states are ≈127, 9.5, and 1.5 for HC5N, HC7N, and HC9N, respectively. We find that these lowest-lying vibrational states are most probably populated via infrared pumping to vibrationally excited states lying at ≈600 cm-1. The lowest vibrationally excited states thus need to be taken into account to precisely determine absolute abundances and abundance ratios for long carbon chains. The abundance ratios N(HC5N)/N(HC7N) and N(HC7N)/N(HC9N) are 2.4 and 7.7, respectively., he Spanish authors thank Ministerio de Ciencia e Innovación for funding support through project AYA2016-75066-C2-1-P. We also thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS. MA thanks Ministerio de Ciencia e Innovación for Ramón y Cajal grant RyC2014-16277. CB thanks Ministerio de Ciencia e Innovación for Juan de la Cierva grant FJCI-2016-27983. LVP acknowledges support from the Swedish Research Council and from the ERC through the consolidator

51 pags., 43 figs., 3 tabs., Context. The carbon-rich envelope of the asymptotic giant branch star CW Leo, IRC+10216, is one of the richest molecular sources in the sky. Available spectral surveys below 51 GHz are more than 25 years old, and new work is needed. Aims. Characterizing the rich molecular content of this source, specially for heavy species, requires carrying out very sensitive spectral surveys at low frequencies. In particular, we have achieved an rms in the range 0.2-0.6mK per MHz. Methods. Long Q band (31.0-50.3 GHz) single-dish integrations were carried out with the Yebes-40m telescope using specifically built receivers. The most recent line catalogs were used to identify the lines. Results. The data contain 652 spectral features, corresponding to 713 transitions from 81 species (we count the isomers, isotopologs, and ortho/para species separately). Only 57 unidentified lines remain with signal-to-noise ratios ≤3. Some new species and/or vibrational modes have been discovered for the first time with this survey. Conclusions. This IRC+10216 spectral survey is by far the most sensitive survey carried out to date in the Q band. It therefore provides the most complete view of IRC+10216 from 31.0 to 50.3 GHz, giving unique information about its molecular content, especially for heavy species. Rotational diagrams built from the data provide valuable information about the physical conditions and chemical content of this circumstellar envelope., We thank Ministerio de Ciencia e Innovación of Spain for funding support through projects PID2019-106110GB-I00, PID2019- 107115GB-C21/AEI/10.13039/501100011033, PID2019-106235GB-I00, and grant FJCI-2016-27983 for CB. We also thank ERC for funding through grant ERC-2013-Syg-610256-NANOCOSMOS. M.A. thanks MICIU for grant RyC2014-16277.

5 pags., 1 fig., 4 tabs., We report the first detection in space of the single deuterated isotopologue of methyldiacetylene, CH2DC4H. A total of 12 rotational transitions, with J = 8-12 and Ka = 0 and 1, were identified for this species in TMC-1 in the 31.0-50.4 GHz range using the Yebes 40m radio telescope. The observed frequencies allowed us to obtain, for the first time, the spectroscopic parameters of this deuterated isotopologue. We derived a column density of (5.5 ± 0.2) × 1011 cm-2. The abundance ratio between CH3C4H and CH2DC4H is 24 ± 2. This ratio is similar to that found for the CH3C3N/CH2DC3N analogue system, which is 22 ± 2. We did not detect the deuterated species CH3C4D, which has already been observed in laboratory experiments. The detection of deuterated CH3C4H allows us to extend the discussion on the chemical mechanisms of deuterium fractionation at work in TMC-1 using a new gas-phase chemical model with multiply deuterated molecules. Introducing a possible deuterium exchange reaction between CH3CCH and atomic deuterium allows us to account for the CH3C4H/CH2DC4H abundance ratio., We thank ERC for funding through grant ERC-2013-Syg610256-NANOCOSMOS. The Spanish authors thank Ministerio de Ciencia e Innovación for funding support through projects PID2019-106235GB-I00 and PID2019-107115GB-C21/AEI/10.13039/501100011033. M. A. thanks Ministerio de Ciencia e Innovación for grant RyC-2014-16277. E. R. acknowledges the support of the Programme National ‘Physique et Chimie du Milieu Interstellaire’ (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES. Several kinetic data we used have been taken from the online databases KIDA (Wakelam et al. (2012), https://kida.astrochem-tools.org/) and UMIST2012 (McElroy et al. (2013), http://udfa.ajmarkwick.net).

6 pags., 2 figs., 3 tabs., We report the detection of the propargyl radical (CH2CCH) in the cold dark cloud TMC-1 in the λ 3 mm wavelength band. We recently discovered this species in space toward the same source at a wavelength of λ 8 mm. In those observations, various hyperfine components of the 20,2-10,1 rotational transition, at 37.5 GHz, were detected using the Yebes 40 m telescope. Here, we used the IRAM 30 m telescope to detect ten hyperfine components of the 50,5-40,4 rotational transition, lying at 93.6 GHz. The observed frequencies differ by 0.2 MHz with respect to the predictions from available laboratory data. This difference is significant for a radio-Astronomical search for CH2CCH in interstellar sources with narrow lines. We thus included the measured frequencies in a new spectroscopic analysis to provide accurate frequency predictions for the interstellar search for propargyl at millimeter wavelengths. Moreover, we recommend that future searches for CH2CCH in cold interstellar clouds be carried out at λ 3 mm rather than at λ 8 mm. The 50,5-40,4 transition is about five times more intense than the 20,2-10,1 one in TMC-1, which implies that detecting the former requires about seven times less telescope time than detecting the latter. We constrain the rotational temperature of CH2CCH in TMC-1 to 9.9 ± 1.5 K, which indicates that the rotational levels of this species are thermalized at the gas kinetic temperature. The revised value of the column density of CH2CCH (including ortho and para species) is (1.0 ± 0.2) × 1014 cm-2, and thus the CH2CCH/CH3CCH abundance ratio is revised slightly higher, approaching one. This study opens the door to future detections of CH2CCH in other cold interstellar clouds, making it possible to further investigate the role of this very abundant hydrocarbon radical in the synthesis of large organic molecules, such as aromatic rings., We acknowledge funding support from Spanish Ministerio de Ciencia e Innovación through grants PID2019-106110GB-I00, PID2019- 107115GB-C21, and PID2019-106235GB-I00 and from the European Research Council (ERC Grant 610256: NANOCOSMOS). M.A. also acknowledges funding support from the Ramón y Cajal programme of Spanish Ministerio de Ciencia e Innovación (grant RyC-2014-16277).

6 pags., 3 figs., 6 tabs., Context. Nitriles constitute almost 15% of the molecules observed in the interstellar medium (ISM), surprisingly only two dinitriles have been detected in the ISM so far. The lack of astronomical detections for dinitriles may be partly explained by the absence of laboratory rotational spectroscopic data. Aims. Our goal is to investigate the rotational spectrum of glutaronitrile, NC-CH-CH-CH-CN, in order to allow its possible detection in the ISM. Methods. The rotational spectrum of glutaronitrile was measured using two different experimental setups. A Fourier transform microwave spectrometer was employed to observe the supersonic jet rotational spectrum of glutaronitrile between 6 and 20 GHz. In addition, the mmW spectrum was observed in the frequency range 72-116.5 GHz using a broadband millimetre-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches were supported by high-level ab initio calculations. Results. A total of 111 rotational transitions with maximum values of J and K quantum numbers 54 and 18, respectively, were measured for the gg conformer of glutaronitrile. The analysis allowed us to accurately determine the rotational, nuclear quadrupole coupling, quartic and sextic centrifugal distortion constants. These rotational parameters were employed to search for glutaronitrile in the cold and warm molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm. Glutaronitrile was not detected, and the upper limits' column densities were derived. Those are a factor of 1.5 and 5 lower than those obtained for the total column densities of the analogous succinonitrile in Orion KL and Sgr B2, respectively., We thank the European Research Council for funding support under Synergy Grant ERC-2013-SyG, G.A. 610256 (NANOCOSMOS). CB thanks to Ministerio de Ciencia, Innovación y Universidades for a Juan de la Cierva postdoctoral fellowship (FJCI-2016-27983). YE thanks to the Ministry of Science and Technology of Taiwan for the Grant MOST 104-2113-M-009- 020. This work was also based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the new, ultra-stable, double channel spectrograph at the 3.5 m Calar Alto telescope. We computed their stellar atmospheric parameters (Teti, log g, 4, and [Fell I]) by means of the STEPAR code, a PYTHON implementation of the equivalent width method that employs the 2017 version of the MOOG code and a grid of MARCS model atmospheres. We compiled four Fe 1 and Fe tl line lists suited to metal-rich dwarfs, metal-poor dwarfs, metal-rich giants, and metal-poor giants that cover the wavelength range from 5300 to 17 100 A, thus substantially increasing the number of identified Fe! and Felt lines up to 653 and 23, respectively, We examined the impact of the near-infrared Fe and Fen lines upon our parameter determinations after an exhaustive literature search, placing special emphasis on the 14 Gala benchmark stars contained in our sample, Even though our parameter determinations remain in good agreement with the literature values, the increase in the number of Fel and Feu lines when the near-infrared region is taken into account reveals a deeper Teff scale that might stem from a higher sensitivity of the near-infrared lines to Tff.C 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society, CARMENES is an instrument for the Centro Astronomico Hispano en Andaluc ' ia at Calar Alto (CAHA). CARMENES is funded by the German Max-Plank Gesellschaft (MPG), the Spanish Consejo Superior de InvestigacionesCientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Plank-Institut fur Astronomie, Instituto de Astrofisica deAndalucia, LandessternwarteKonigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenberg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano en Andalucia), with additional contributions by the Ministerio de Asuntos Economicos y Transformacion Digital, the German Research Foundation (DFG) through the Major Research Instrumentation Programme and DFG Research Unit FOR2544 Blue Planets around Red Stars', the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. The authors acknowledge financial support from the Fundacao para a Ciencia e a Tecnologia (FCT) through national funds (PTDC/FIS-AST/28953/2017) and by Fundo Europeu de Desenvolvimento Regional (FEDER) through COMPETE2020 -Programa Operacional Competitividade e Internacionalizacao (POCI01-0145-FEDER-028953), the Ministerio de Ciencia e Innovacion through fellowship FPU15/01476, and projects AYA2016-79425C3-1/2/3-P, and the Universidad Complutense de Madrid. JIGH acknowledges financial support from the Ministerio de Ciencia e Innovacion under the 2013 Ramon y Cajal programme RYC-201314875, and from the project AYA2017-86389-P. This work has made use of the VALD database, operated at Uppsala University, the Institute of Astronomy RAS in Moscow, and the University of Vienna. We thank Calar Alto Observatory for the allocation of director's discretionary time to this programme. EM would also like to warmly thank the staff at the Hamburger Sternwarte for their hospitality during his stay funded by project EST18/00162 from the Ministerio de Ciencia e Innovacion. Based on data from the CARMENES data archive at CAB (INTA-CSIC).

8 pags., 5 figs., 3 apps., We report on the detection of hot CO2 in the O-rich asymptotic giant branch star R Leo based on high spectral resolution observations in the range 12.8-14.3 μm carried out with the Echelon-cross-Echelle Spectrograph (EXES) mounted on the Stratospheric Observatory for Infrared Astronomy (SOFIA). We found ≈ 240 CO2 emission lines in several vibrational bands. These detections were possible thanks to a favorable Doppler shift that allowed us to avoid contamination from telluric CO2 features. The highest excitation lines involve levels at an energy of ≈ 7000 K. The detected lines are narrow (average deconvolved width ≈ 2.5 km s-1) and weak (usually ≤ 10% the continuum). A ro-vibrational diagram shows that there are three different populations, warm, hot, and very hot, with rotational temperatures of ≈ 550, 1150, and 1600 K, respectively. From this diagram, we derived a lower limit for the column density of ≈ 2.2 × 1016 cm-2. Further calculations based on a model of the R Leo envelope suggest that the total column density can be as large as 7.0 × 1017 cm-2 and the abundance with respect to H2 ≈ 2.5 × 10-5. The detected lines are probably formed due to the de-excitation of CO2 molecules from high energy vibrational states, which are essentially populated by the strong R Leo continuum at 2.7 and 4.2 μm., The research leading to these results has received funding support from the European Research Council under the European Union’s Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement n. 610256 NANOCOSMOS. EJM acknowledges financial support for this work through award #06_0144 which was issued by USRA and provided by NASA MJR and EXES observations are supported by NASA cooperative agreement 80NSSC19K1701. Based on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart.

Context. Phosphorus-bearing species are essential to the formation of life on Earth, however they have barely been detected in the interstellar medium. In particular, towards star-forming regions only PN and PO have been identified so far. Since only a small number of detections of P-bearing molecules are available, their chemical formation pathways are not easy to constrain and are thus highly debatable. An important factor still missing in the chemical models is the initial elemental abundance of phosphorus, that is, the depletion level of P at the start of chemical models of dense clouds. Aims. In order to overcome this problem, we study P-bearing species in diffuse and translucent clouds. In these objects phosphorus is expected to be mainly in the gas phase and therefore the elemental initial abundance needed in our chemical simulations corresponds to the cosmic one and is well constrained. Methods. For the study of P-bearing chemistry we used an advanced chemical model. We updated and significantly extended the P-chemistry network based on chemical databases and previous literature. We performed single-pointing observations with the IRAM 30 m telescope in the 3 mm range towards the line of sight to the strong continuum source B0355+508 aiming for the (2-1) transitions of PN, PO, HCP, and CP. This line of sight incorporates five diffuse and/or translucent clouds. Results. The (2-1) transitions of the PN, PO, HCP, and CP were not detected. We report high signal-to-noise-ratio detections of the (1-0) lines of 13CO, HNC, and CN along with a first detection of C34S towards this line of sight. We have attempted to reproduce the observations of HNC, CN, CS, and CO in every cloud with our model by applying typical physical conditions for diffuse or translucent clouds. We find that towards the densest clouds with vLSR = -10, - 17 km s-1 the best-fit model is given by the parameters (n(H), AV, Tgas) = (300 cm-3, 3 mag, 40 K). Conclusions. According to our best-fit model, the most abundant P-bearing species are HCP and CP (~10-10). The molecules PN, PO, and PH3 also show relatively high predicted abundances of ~10-11. We show that the abundances of these species are sensitive to visual extinction, cosmic-ray ionization rate, and the diffusion-to-desorption energy ratio on dust grains. The production of P-bearing species is favored towards translucent rather than diffuse clouds, where the environment provides a stronger shielding from the interstellar radiation. Based on our improved model, we show that the (1-0) transitions of HCP, CP, PN, and PO are expected to be detectable with estimated intensities of up to ~200 mK. © J. Chantzos et al. 2020. Horizon 2020 Framework Programme, H2020: 66493 lzp-2018/1-0170 We thank the anonymous referee for his/her comments that significantly improved the present manuscript. The authors also wish to thank the IRAM Granada staff for their help during the observations. V.M.R. has received funding from the European Unions Horizon 2020 research and innovation programme under the Marie Skodowska-Curie grant agreement No 66493. Work by A.V. is supported by the Latvian Science Council via the project lzp-2018/1-0170. J.C. acknowledges Dr. J. C. Laas for his support with the Python programming.

8 pags., 5 figs., 5 tabs., 1 app., Context. Dinitriles with a saturated hydrocarbon skeleton and a −C≡N group at each end can have large electric dipole moments. Their formation can be related to highly reactive radicals such as CH2CN, C2N, or CN. Thus, these saturated dinitriles are potential candidates to be observed in the interstellar medium (ISM). Aims. Our goal is the investigation of the rotational spectrum of one of the simplest dinitriles N≡C−CH2−CH2−C≡N, succinonitrile, whose actual rotational parameters are not precise enough to allow its detection in the ISM. In addition, the rotational spectra for its vibrational excited states will be analysed. Methods. The rotational spectra of succinonitrile was measured in the frequency range 72−116.5 GHz using a new broadband millimeter-wave spectrometer based on radio astronomy receivers with Fast Fourier Transform backends. The identification of the vibrational excited states of succinonitrile was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. Results. A total of 459 rotational transitions with maximum values of J and Ka quantum numbers 70 and 14, respectively, were measured for the ground vibrational state of succinonitrile. The analysis allowed us to accurately determine the rotational, quartic, and sextic centrifugal distortion constants. Up to eleven vibrational excited states, resulting from the four lowest frequency vibrational modes ν13, ν12, ν24, and ν23 were identified. In addition to the four fundamental modes, we observed overtones together with some combination states. The rotational parameters for the ground state were employed to unsuccessfully search for succinonitrile in the cold and warm molecular clouds Orion KL, Sgr B2(N), B1-b, and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm and the Yebes 40 m at 1.3 cm and 7 mm., We thank the European Research Council for funding support under Synergy Grant ERC-2013-SyG, G.A. 610256 (NANOCOSMOS). CB would like to thank the Ministerio de Ciencia, Innovación y Universidades for a Juan de la Cierva postdoctoral fellowship (FJCI-2016-27983). IT, VJH, and JLD acknowledge additional partial support from the Spanish State Research Agency (AEI) through grant FIS2016-77726-C3-1-P. This work was also based on observations carried out with the IRAM 30-meter telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

5 pags., 2 figs., We report on the detection of calcium isocyanide, CaNC, in the carbon-rich evolved star IRC+10216. We derived a column density for this species of (2 ± 0.5) × 1011 cm−2 . Based on the observed line profiles and the modelling of its emission through the envelope, the molecule has to be produced in the intermediate and outer layers of the circumstellar envelope where other metal-isocyanides have previously been found in this source. The abundance ratio of CaNC relative to MgNC and FeCN is '1/60 and '1, respectively. We searched for the species CaF, CaCl, CaC, CaCCH, and CaCH3 for which accurate frequency predictions are available. Only upper limits have been obtained for these molecules., The Spanish authors thank the Ministerio de Ciencia Innovación y Universidades for funding support from the CONSOLIDER-Ingenio program “ASTROMOL” CSD 2009-00038, AYA2012-32032, AYA2016-75066- C2-1-P. We also thank the ERC for funding through grant ERC-2013-Syg610256-NANOCOSMOS. MA thanks the Ministerio de Ciencia Innovación y Universidades for the Ramón y Cajal grant RyC-2014-16277. CB thanks the Ministerio de Ciencia Innovación y Universidades for the Juan de la Cierva grant FJCI-2016-27983. LVP acknowledges support from the Swedish Research Council and ERC consolidator grant 614264.

8 pags., 8 figs., 5 tabs., We report the detection, for the first time in space, of cyano thioformaldehyde (HCSCN) and propynethial (HCSCCH) towards the starless core TMC-1. Cyano thioformaldehyde presents a series of prominent a- and b-type lines, which are the strongest previously unassigned features in our Q-band line survey of TMC-1. Remarkably, HCSCN is four times more abundant than cyano formaldehyde (HCOCN). On the other hand, HCSCCH is five times less abundant than propynal (HCOCCH). Surprisingly, we find an abundance ratio HCSCCH/HCSCN of ∼0.25, in contrast with most other ethynyl-cyanide pairs of molecules for which the CCH-bearing species is more abundant than the CN-bearing one. We discuss the formation of these molecules in terms of neutral-neutral reactions of S atoms with CH2CCH and CH2CN radicals as well as of CCH and CN radicals with H2CS. The calculated abundances for the sulphur-bearing species are, however, significantly below the observed values, which points to an underestimation of the abundance of atomic sulphur in the model or to missing formation reactions, such as ion-neutral reactions., This research has been funded by ERC through grant ERC-2013-Syg-610256-NANOCOSMOS. Authors also thank Ministerio de Ciencia e Innovación (Spain) for funding support through projects AYA2016-75066-C2-1-P, PID2019-106235GB-I00 and PID2019-107115GBC21/AEI/10.13039/501100011033. MA thanks Ministerio de Ciencia e Innovación for grant RyC-2014-16277. YE thanks Ministry of Science and Technology, Taiwan, for grant No. MOST 108-2113-M-009-025 and MOST 108- 2811-M-009-520.

8 pags., 3 figs., 7 tabs., Context. At least a dozen molecules with a formyl group (HCO) have been observed to date in the interstellar medium (ISM), suggesting that other such species exist and remain to be discovered. However, there is still a lack of high-resolution spectroscopic data for simple molecular species of this type that could provide a basis for their detection. Aims. Cyclopropanecarboxaldehyde, c-C3H5CHO, is a small molecule containing a formyl group and is therefore an interesting candidate for astrophysical detection. The rotational spectrum of cyclopropanecarboxaldehyde has been observed before, but its experimental rotational parameters are not precise enough to allow its detection in the millimetre-wave domain. Methods. We measured the rotational spectrum of cyclopropanecarboxaldehyde in the frequency ranges 31.5-50 GHz and 72-116.5 GHz using the GACELA (GAS CEll for Laboratory Astrophysics) broadband high-resolution rotational spectrometer constructed at the Yebes Observatory. The spectroscopic study was supported by high-level theoretical calculations which were used in the identification of the vibrational excited states of cyclopropanecarboxaldehyde. Results. Our analysis of the rotational spectrum of cyclopropanecarboxaldehyde allowed us to obtain accurate rotational parameters for the ground state of both cis and trans isomers, which were used to derive sufficiently reliable predictions up to 300 GHz. In addition to the ground states, we identified 12 and 6 vibrationally excited states for the trans and cis isomers, respectively, including fundamental modes, multiple excitation quanta, and combination states. We find that the gas phase concentration of the trans isomer is almost 1.2 times larger than that of the cis one. These new experimental rotational parameters were employed to search for cyclopropanecarboxaldehyde in the warm molecular clouds Orion KL and Sgr B2(N) using the spectral surveys captured by ALMA (Orion) and IRAM 30 m (Sgr) at 1 and 3 mm, respectively., We thank the European Research Council for funding support under Synergy Grant ERC-2013-SyG, G.A. 610256 (NANOCOSMOS). We also thank Ministerio de Ciencia e Innovación for funding support through projects AYA2016-75066-C2-1-P and PID2019-107115GB-C21. B.T. also thanks the Spanish MICIU for funding support from grant PID2019-106235GB-I00. C.B. thanks to Ministerio de Ciencia, Innovación y Universidades for a Juan de la Cierva postdoctoral fellowship (FJCI-2016-27983). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00009.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan) 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.

1 pag. -- Erratum: A&A 642, L17 (2020), https://doi.org/10.1051/0004-6361/202039351, IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain)

8 pags., 4 figs., 7 tabs., Using the Yebes 40m and IRAM 30m radio telescopes, we detected a series of harmonically related lines with a rotational constant B0 = 4460.590 ± 0.001 MHz and a distortion constant D0 = 0.511 ± 0.005 kHz towards the cold dense core TMC-1. High-level-of-theory ab initio calculations indicate that the best possible candidate is protonated tricarbon monoxide, HC3O+. We have succeeded in producing this species in the laboratory and observed its Ju-Jl = 2-1 and 3-2 rotational transitions. Hence, we report the discovery of HC3O+ in space based on our observations, theoretical calculations, and laboratory experiments. We derive an abundance ratio N(C3O)/N(HC3O+) ∼7. The high abundance of the protonated form of C3O is due to the high proton affinity of the neutral species. The chemistry of O-bearing species is modelled, and predictions are compared to the derived abundances from our data for the most prominent O-bearing species in TMC-1., The Spanish authors thank Ministerio de Ciencia e Innovación for funding support through projects AYA2016-75066-C2-1-P, PID2019-107115GB-C21. We also thank ERC for funding through Grant ERC-2013-Syg-610256-NANOCOSMOS. M. A. and C. B. thanks MICIN for grants RyC-2014-16277 and FJCI-2016-27983, respectively. Y. Endo thanks Ministry of Science and Technology of Taiwan through Grant MOST108-2113- M-009-25.

As a candidate 'super-Chandrasekhar' or 09dc-like Type Ia supernova (SN Ia), SN 2012dn shares many characteristics with other members of this remarkable class of objects but lacks their extraordinary luminosity. Here, we present and discuss the most comprehensive optical data set of this SN to date, comprised of a densely sampled series of early-time spectra obtained within the Nearby Supernova Factory project, plus photometry and spectroscopy obtained at the Very Large Telescope about 1 yr after the explosion. The light curves, colour curves, spectral time series, and ejecta velocities of SN 2012dn are compared with those of other 09dc-like and normal SNe Ia, the overall variety within the class of 09dc-like SNe Ia is discussed, and new criteria for 09dc-likeness are proposed. Particular attention is directed to additional insight that the late-phase data provide. The nebular spectra show forbidden lines of oxygen and calcium, elements that are usually not seen in late-time spectra of SNe Ia, while the ionization state of the emitting iron plasma is low, pointing to low ejecta temperatures and high densities. The optical light curves are characterized by an enhanced fading starting ∼60 d after maximum and very low luminosities in the nebular phase, which is most readily explained by unusually early formation of clumpy dust in the ejecta. Taken together, these effects suggest a strongly perturbed ejecta density profile, which might lend support to the idea that 09dc-like characteristics arise from a brief episode of interaction with a hydrogen-deficient envelope during the first hours or days after the explosion.

The formyl radical HCO has been proposed as the basic precursor of many complex organic molecules such as methanol (CH$_3$OH) or glycolaldehyde (CH$_2$OHCHO). Using ALMA, we have mapped, for the first time at high angular resolution ($\sim$1$^{\prime\prime}$, $\sim$140 au), HCO towards the Solar-type protostellar binary IRAS 16293$-$2422, where numerous complex organic molecules have been previously detected. We also detected several lines of the chemically related species H$_2$CO, CH$_3$OH and CH$_2$OHCHO. The observations revealed compact HCO emission arising from the two protostars. The line profiles also show redshifted absorption produced by foreground material of the circumbinary envelope that is infalling towards the protostars. Additionally, IRAM 30m single-dish data revealed a more extended HCO component arising from the common circumbinary envelope. The comparison between the observed molecular abundances and our chemical model suggests that whereas the extended HCO from the envelope can be formed via gas-phase reactions during the cold collapse of the natal core, the HCO in the hot corinos surrounding the protostars is predominantly formed by the hydrogenation of CO on the surface of dust grains and subsequent thermal desorption during the protostellar phase. The derived abundance of HCO in the dust grains is high enough to produce efficiently more complex species such as H$_2$CO, CH$_3$OH, and CH$_2$OHCHO by surface chemistry. We found that the main formation route of CH$_2$OHCHO is the reaction between HCO and CH$_2$OH., Comment: Accepted in Monthly Notices of the Royal Astronomical Society; 19 pages, 12 figures, 7 tables

As a candidate 'super-Chandrasekhar' or 09dc-like Type Ia supernova (SN Ia), SN 2012dn shares many characteristics with other members of this remarkable class of objects but lacks their extraordinary luminosity. Here, we present and discuss the most comprehensive optical data set of this SN to date, comprised of a densely sampled series of early-time spectra obtained within the Nearby Supernova Factory project, plus photometry and spectroscopy obtained at the VLT about 1 yr after the explosion. The light curves, colour curves, spectral time series and ejecta velocities of SN 2012dn are compared with those of other 09dc-like and normal SNe Ia, the overall variety within the class of 09dc-like SNe Ia is discussed, and new criteria for 09dc-likeness are proposed. Particular attention is directed to additional insight that the late-phase data provide. The nebular spectra show forbidden lines of oxygen and calcium, elements that are usually not seen in late-time spectra of SNe Ia, while the ionisation state of the emitting iron plasma is low, pointing to low ejecta temperatures and high densities. The optical light curves are characterised by an enhanced fading starting ~60 d after maximum and very low luminosities in the nebular phase, which is most readily explained by unusually early formation of clumpy dust in the ejecta. Taken together, these effects suggest a strongly perturbed ejecta density profile, which might lend support to the idea that 09dc-like characteristics arise from a brief episode of interaction with a hydrogen-deficient envelope during the first hours or days after the explosion., Comment: 16 pages, 11 figures, MNRAS in press, missing line added in Table 1