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1. The Statistical Analysis of Exoplanet and Host Stars Based on Multi-Satellite Data Observations

Author

Yanke Tang, Xiaolu Li, Kai Xiao, Ning Gai, Shijie Li, Futong Dong, Yifan Wang, and Yang Gao

Subjects
planet, transiting exoplanets, planet formation rate, planet classification, giant planets, minor planets, Elementary particle physics, QC793-793.5
Abstract

In recent years, the rapid development of exoplanet research has provided us with an opportunity to better understand planetary systems in the universe and to search for signs of life. In order to further investigate the prevalence of habitable exoplanets and to validate planetary formation theories, as well as to comprehend planetary evolution, we have utilized confirmed exoplanet data obtained from the NASA Exoplanet Archive database, including data released by telescopes such as Kepler and TESS. By analyzing these data, we have selected a sample of planets around F, G, K, and M-type stars within a radius range of 1 to 20 R⊕ and with orbital periods ranging from 0.4 days to 400 days. Using the IDEM method based on these data, we calculated the overall formation rate, which is estimated to be 2.02%. Then, we use these data to analyze the relationship among planet formation rates, stellar metallicity, and stellar gravitational acceleration (logg). We firstly find that the formation rate of giant planets is higher around metal-rich stellars, but it inhibits the formation of gas giants when logg > 4.5, yet the stellar metallicity seems to have no effect on the formation rate of smaller planets. Secondly, the host stellar gravitational acceleration affects the relationship between planet formation rate and orbital period. Thirdly, there is a robust power-law relationship between the orbital period of smaller planets and their formation rate. Finally, we find that, for a given orbital period, there is a positive correlation between the planet formation rate and the logg.

Published
2024
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2. Unsupervised Horizontal Pyramid Similarity Learning for Cross-Domain Adaptive Person Re-Identification

Author

Wenhui Dong, Peishu Qu, Chunsheng Liu, Yanke Tang, and Ning Gai

Subjects
Person re-identification, unsupervised deep learning, unsupervised cross domain adaption, horizontal pyramid similarity learning, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

Although person re-identification has made great progress, unsupervised cross-domain adaptive person re-identification is still a challenging problem. With no labeled data in target domain, the performance may have a significant drop. In this paper, we propose an unsupervised cross-domain adaptive person re-identification framework based on horizontal pyramid similarity learning (UHPS). Firstly, horizontal pyramid features are extracted by dividing the deep feature maps into different number of partial feature bins. These feature bins with diverse scales can incorporate not only the global information but also local information in different spatial scales, making the framework more robust in complex environment. Then, horizontal pyramid similarity learning is proposed with the mechanism of fusing together the internal similarity of the target domain and the similarity between the source domain and target domain. Finally, the unsupervised clustering algorithm DBSCAN embeded with the horizontal pyramid similarity is employed to select training data in the target domain and estimate the pseudo labels in each training iteration, for the purpose of adapting the framework to the target domain. The results on Market1501 and DukeMTMC-reID confirm that the proposed framework can adapt to the target domain effectively and outperforms the state-of-the-art unsupervised cross domain person re-identification approaches.

Published
2021
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6. Sounding open clusters: asteroseismic constraints from Kepler on the properties of NGC 6791 and NGC 6819

Author

Basu, Sarbani, Grundahl, Frank, Stello, Dennis, Kallinger, Thomas, Hekker, Saskia, Mosser, Benoit, Garcia, Rafael A., Mathur, Savita, Brogaard, Karsten, Bruntt, Hans, Chaplin, William J., Elsworth, Ning Gai Yvonne, Esch, Lisa, Ballot, Jerome, Bedding, Timothy R., Gruberbauer, Michael, Huber, Daniel, Miglio, Andrea, Yildiz, Mutlu, Kjeldsen, Hans, Christensen-Dalsgaard, Joergen, Gilliland, Ronald L., Fanelli, Michael M., Ibrahim, Khadeejah A., and Smith, Jeffrey C.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present initial results on some of the properties of open clusters NGC 6791 and NGC 6819 derived from asteroseismic data obtained by NASA's Kepler mission. In addition to estimating the mass, radius and log g of stars on the red-giant branch of these clusters, we estimate the distance to the clusters and their ages. Our model-independent estimate of the distance modulus of NGC 6791 is (m-M)_0= 13.11\pm 0.06. We find (m-M)_0= 11.85\pm 0.05 for NGC 6819. The average mass of stars on the red-giant branch of NGC 6791 is 1.20 \pm 0.01 M_sun, while that of NGC 6819 is 1.68\pm 0.03M_sun. It should be noted that we do not have data that cover the entire red-giant branch and the actual mass will be somewhat lower. We have determined model-dependent estimates of ages of these clusters. We find ages between 6.8 and 8.6 Gyr for NGC 6791, however, most sets of models give ages around 7Gyr. We obtain ages between 2 and 2.4 Gyr for NGC 6819., Comment: Published in Astrophys. J. Letters

Published
2011
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8. Evidence of Quasi-periodic Oscillation in the Optical Band of the Blazar 1ES 1959+650

Author

Fu-Tong Dong, Ning Gai, Yanke Tang, Yi-Fan Wang, and Ting-Feng Yi

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

We analyzed the optical monitoring data in the R band of TeV blazar 1ES 1959+650 from 2002 to 2018, and provided evidence of a quasi-periodic oscillation in this object. The light curve shows a stable and persistent periodicity at ∼540 days, detected by the Lomb–Scargle periodogram, Jurkevich and weighted wavelet z-transform techniques. The red noise power spectrum was estimated using the PSRESP method, and this period was found to be at >3σ significance level. There are also two possible periodicities at ∼268 and ∼1100 days detected by all three methods. However, their significance levels are relatively low, and thus these two periods cannot be verified by the present data. We discuss several possible physical models that could explain the periodic variability in this object.

Published
2022
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9. The Asteroseismology Analysis of 14 Solar-like Stars Based on TESS and LAMOST Observations

Author

Ning Gai, Yanke Tang, Zhikai Li, Yang Huang, Wenhui Dong, and Xiaoshuang Zhou

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

The Transiting Exoplanet Survey Satellite (TESS) is performing a near all-sky survey for planets that transit bright stars. It provides excellent photometric data for asteroseismology of solar-like stars that exhibit oscillation by a convection-driven mechanism. In this paper, we analyze the light curves of 14 stars that are observed by TESS. These stars mainly focus on Sector 21 and the other Sectors intersecting with Sector 21. Through crossmatching with the LAMOST surveys, 14 stars with signals of solar-like oscillations are selected, and asteroseismic analysis is present. The frequency of maximum power ν max and the large frequency separation Δν are extracted from its frequency power spectrum using the pySYD pipeline. Scaling relations are an attractive method that can easily and immediately be applied to observations to derive the stellar properties. To validate the different calibrated scaling relations for 14 TESS stars, the fundamental stellar properties are estimated by the relations and compared with grid-based modeling results, which use the constraints of global asteroseismic parameters and nonasteroseismic parameters. The new red-giant branch (RGB) scaling relations are found to overestimate the radius and mass when compared to the grid results, while the f Δν scaling relations lead to overall lower radius and mass estimates. The average uncertainties of these stars from grid modeling are within 2% in the radius and 3% in the mass. Regardless of the method, we can get almost equally good results of log g for all the stars. Besides the grid method, the new RGB scaling relations for ages provide a simple and accurate method to determine the stellar ages.

Published
2022
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10. Stellar populations of galaxies in the LAMOST spectral survey

Author

Li-Li Wang, Shi-Yin Shen, A-Li Luo, Guang-Jun Yang, Ning Gai, Yan-Ke Tang, Meng-Xin Wang, Li Qin, Jin-Shu Han, and Li-Xia Rong

Subjects
Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics
Abstract

We firstly derive the stellar population properties: age and metallicity for $\sim$ 43,000 low redshift galaxies in the seventh data release (DR7) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey, which have no spectroscopic observations in the Sloan Digital Sky Survey(SDSS). We employ a fitting procedure based on the small-scale features of galaxy spectra so as to avoid possible biases from the uncertain flux calibration of the LAMOST spectroscopy. We show that our algorithm can successfully recover the average age and metallicity of the stellar populations of galaxies down to signal-to-noise$\geq$5 through testing on both mock galaxies and real galaxies comprising LAMOST and their SDSS counterparts. We provide a catalogue of the age and metallicity for $\sim$ 43,000 LAMOST galaxies online. As a demonstration of the scientific application of this catalogue, we present the Holmberg effect on both age and metallicity of a sample of galaxies in galaxy pairs., Comment: 15 pages, 9 Postscript figures, accepted for publication in The Astrophysical Journal Supplement Series

Published
2021
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11. The First Photometric Analysis of Two Low Mass Ratio Totally Eclipsing Contact Binaries: TIC 393943031 and TIC 89428764

Author

Yan-Ke Tang, Ya-Ni Guo, Kai Li, Ning Gai, and Zhi-Kai Li

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

Photometric analysis of the contact binaries TIC 393943031 and TIC 89428764 was carried out using Transiting Exoplanet Survey Satellite and SuperWASP data for the first time. Using the Wilson–Devinney code, we have found that TIC 393943031 is a low-mass-ratio deep contact binary with a fillout factor of 50.9(±1)% and a mass ratio of q = 0.163 ± 0.001. TIC 89428764 is a medium and low-mass-ratio contact binary with a fillout factor of 34.5(±1)% and a mass ratio of q = 0.147 ± 0.001. Furthermore, the period study reveals both the stars exhibit continuously increasing periods, the increasing rate is 4.21 × 10−7 day yr−1 for TIC 393943031 while 6.36 × 10−7 day yr−1 for TIC 89428764. The possible reason is mass transfer from the secondary component to the primary component for both stars. Meanwhile, we discussed their evolutionary phases and orbital angular momenta.

Published
2022
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13. Asteroseismic Investigations of the Binary System HD176465

Author

Sarbani Basu, Ning Gai, and Yanke Tang

Subjects
Physics, Astrophysics - Solar and Stellar Astrophysics, 010308 nuclear & particles physics, Space and Planetary Science, 0103 physical sciences, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Binary system, 010303 astronomy & astrophysics, 01 natural sciences, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

HD 176465 is a binary system whose both components are solar-like pulsators and whose oscillation frequencies were observed by the \kepler\ mission. In this paper we have modeled the asteroseismic and spectroscopic data of the stars, and have determined their convection-zone helium abundances using the signatures left by the He{\sc ii} ionization zone on the mode frequencies. As expected we find that the components of the binary have the same age within uncertainties ($3.087 \pm 0.580$ Gyr and $3.569 \pm 0.912$ Gyr); they also have the same initial helium abundance (Y$_{\mathrm{init}}$=0.253 $\pm$ 0.006 and 0.254 $\pm$ 0.008). Their current metallicity ([Fe/H]=$-0.275 \pm 0.04$ and $-0.285 \pm 0.04$) is also the same within errors. Fits to the signature of the He{\sc ii} acoustic glitch yields current helium abundances of $Y_{\rm A} = 0.224 \pm 0.006$ and $Y_{\rm B} = 0.233 \pm 0.008$ for the two components. Analyzing the complete ensemble of models generated for this investigation we find that both the amplitude and acoustic depth of the glitch signature arising from the second helium ionization zone and the base of the convection zone (CZ) are functions of mass. We show that the acoustic depths of these glitches are positively correlated with each other. The analysis can help us to detect the internal structure and constrain the chemical compositions., 32 pages, 10 figures and 3 tables. This paper has been accepted by ApJ on 20 February 2018

Published
2018

14. MYB_SH[AL]QKY[RF] transcription factors MdLUX and MdPCL-like promote anthocyanin accumulation through DNA hypomethylation and MdF3H activation in apple.

Author

Li, Wen-Fang, Ning, Gai-Xing, Zuo, Cun-Wu, Chu, Ming-Yu, Yang, Shi-Jin, Ma, Zong-Huan, Zhou, Qi, Mao, Juan, and Chen, Bai-Hong

Subjects
*FRUIT skins, *ANTHOCYANINS, *TRANSCRIPTION factors, *DNA, *PROMOTERS (Genetics), *ONIONS, *APPLES
Abstract

Heritable DNA methylation is a highly conserved epigenetic mark that is important for many biological processes. In a previous transcriptomic study on the fruit skin pigmentation of apple (Malus domestica Borkh.) cv. 'Red Delicious' (G0) and its four continuous-generation bud sport mutants including 'Starking Red' (G1), 'Starkrimson' (G2), 'Campbell Redchief' (G3) and 'Vallee spur' (G4), we identified MYB transcription factors (TFs) MdLUX and MdPCL-like involved in regulating anthocyanin synthesis. However, how these TFs ultimately determine the fruit skin color traits remains elusive. Here, bioinformatics analysis revealed that MdLUX and MdPCL-like contained a well-conserved motif SH[AL]QKY[RF] in their C-terminal region and were located in the nucleus of onion epidermal cells. Overexpression of MdLUX and MdPCL-like in 'Golden Delicious' fruits, 'Gala' calli and Arabidopsis thaliana promoted the accumulation of anthocyanin, whereas MdLUX and MdPCL - like suppression inhibited anthocyanin accumulation in 'Red Fuji' apple fruit skin. Yeast one-hybrid assays revealed that MdLUX and MdPCL-like may bind to the promoter region of the anthocyanin biosynthesis gene MdF3H. Dual-luciferase assays indicated that MdLUX and MdPCL-like activated MdF3H. The whole-genome DNA methylation study revealed that the methylation levels of the mCG context at the upstream (i.e. promoter region) of MdLUX and MdPCL-like were inversely correlated with their mRNA levels and anthocyanin accumulation. Hence, the data suggest that MYB_SH[AL]QKY[RF] TFs MdLUX and MdPCL-like promote anthocyanin biosynthesis in apple fruit skins through the DNA hypomethylation of their promoter regions and the activation of the structural flavonoid gene MdF3H. [ABSTRACT FROM AUTHOR]

Published
2021
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16. Study on Optimization of Machining Parameters in Electrochemical Machining

Author

Lei Wang and Jiang Ning Gai

Subjects
Engineering, Artificial neural network, Machining, business.industry, Process (engineering), General Engineering, Mechanical engineering, Neural network nn, Research Object, Electrochemical machining, business
Abstract

In electrochemical machining (ECM) machining accuracy of workpieces is greatly influenced by many machining parameters. In this paper the BP neural network model is employed to optimize machining parameters in ECM. Taking a three dimensional complicated surface as the research object the experimental results have shown that the optimization process can be easily operated and the result is of high precision.

Published
2012
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17. Light Curve Periodic Variability of Cyg X-1 using Jurkevich Method

Author

Ai-Jun Dong, Ning Gai, and Yan-Ke Tang

Subjects
Physics, Black hole, Accretion disc, Space and Planetary Science, Astronomy, Astronomy and Astrophysics, Astrophysics, Light curve
Abstract

The Jurkevich method is a useful method to explore periodicity in the unevenly sampled observational data. In this work, we adopted the method to the light curve of Cyg X-1 from 1996 to 2012, and found that there is an interesting period of 370 days, which appears in both low/hard and high/soft states. That period may be correlated with black hole physics and accretion disk geometry.

Published
2014
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18. Asteroseismic study of the red giant ∊ Ophiuchi

Author

Ning Gai, Ling-Huai Li, Yan-Ke Tang, and Shaolan Bi

Subjects
Physics, Convection, Stars, Amplitude, Stellar mass, Space and Planetary Science, Red giant, Metallicity, Astronomy, Astronomy and Astrophysics, Astrophysics
Abstract

We test the possible evolutionary tracks of stars with various masses (1.8 M� , 1.9 M� , 2.0 M� , 2.1 M� , 2.2 M� ) and metallicities Z (0.008, 0.010, 0.012), including both models with and without convective core overshooting. At a given mass and metallicity, the models with a larger overshoot predict a larger radius and age of the star. Based on the observedfrequencyof oscillations and the position of � Oph on the H-R diagram, we obtain two distinct better-fitting models: the solutions with mass M =1 .9 Mfavor a radius in the range 10.55 ± 0.03 Rwith an age of 1.01 ± 0.08Gyr; the solutions with mass M =2 .0 Mfavor a radius in the range 10.74 ± 0.03 Rwith an age of 0.95 ± 0.11Gyr. Furthermore, we investigate the in- fluence of overshooting on the internal structure and the pulsation properties, and find that increasing the convective core overshoot significantly decreases non-radial mode inertia, while also increasing the mode amplitude. Therefore, the estimation of stellar mass and age might be modified by convective core penetration.

Published
2010
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19. Asteroseismology of KIC 8263801: Is It a Member of NGC 6866 and a Red Clump Star?

Author

Yanke Tang, Guy R. Davies, Ning Gai, Sarbani Basu, and Earl P. Bellinger

Subjects
oscillations [stars], solar-type [stars], OSCILLATION FREQUENCIES, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Asteroseismology, PARAMETERS, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, FIELD, 010303 astronomy & astrophysics, Red clump, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, DISTANCES, Physics, 010308 nuclear & particles physics, Spectral density, Astronomy and Astrophysics, Radius, Light curve, GIANT STARS, STELLAR RADII, KEPLER-MISSION, Red-giant branch, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, evolution [stars], OPEN CLUSTERS, ROTATION, MODES, Astrophysics::Earth and Planetary Astrophysics, Open cluster
Abstract

We present an asteroseismic analysis of the Kepler light curve of MC 8263801, a red-giant star in the open cluster NGC 6866 that has previously been reported to be a helium-burning red-clump (RC) star. We extracted the frequencies of the radial and quadrupole modes from its frequency power spectrum and determined its properties using a grid of evolutionary models constructed with MESA. The oscillation frequencies were calculated using the GYRE code and the surface term was corrected using the Ball & Gizon prescription. We find that the star has a mass of M/M-circle dot = 1.793 +/- 0.072, age t = 1.48 +/- 0.21 Gyr, and radius R/R-circle dot = 10.53 +/- 0.28. By analyzing the internal structure of the best-fitting model, we infer the evolutionary status of the star MC 8263801 as being on the ascending part of the red-giant branch, and not on the RC. This result is verified using a purely asteroseismic diagnostic, the epsilon(c) - Delta nu(c), diagram which can distinguish red-giant branch stars from red-clump stars. Finally, by comparing its age with NGC 6866 (t = 0.65 +/- 0.1 Gyr), we conclude that KIC 8263801 is not a member of this open cluster.

Published
2018
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20. Solar-like Oscillations of the Red Giant ɛ Ophiuchi

Author

Ning Gai, Zhi-E. Liu, and Yan-Ke Tang

Subjects
Physics, Red giant, Oscillation, Diagram, Astronomy, Astronomy and Astrophysics, Radius, Astrophysics, Giant star, Space and Planetary Science, Frequency separation, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Solar-like oscillations, Stellar evolution, Astrophysics::Galaxy Astrophysics
Abstract

Solar-like oscillations have recently been observed in the red giant ɛ Ophiuchi (G9.5III). The large frequency separation is found to be 4.8 μHz, non-radial oscillation mode has been shown to exist. Based on the observed frequency of oscillations and the position of ɛ Ophiuchi on the Hertzsprung-Russell diagram and by adopting a method of combined calculation of stellar evolution and oscillations, some preliminary constraints on the mass, metal abundance, age and radius of this star have been obtained.

Published
2008
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21. Modeling ϵ Eri and Asteroseismic Tests of Element Diffusion

Author

Shaolan Bi, Yan-Ke Tang, and Ning Gai

Subjects
Physics, Computation, chemistry.chemical_element, Astronomy and Astrophysics, Astrophysics, Star (graph theory), Radiation, chemistry, Space and Planetary Science, Speed of sound, Astrophysics::Solar and Stellar Astrophysics, Diffusion (business), Element (category theory), Helium
Abstract

Taking into account the helium and metal diffusion, we explore the possible evolutionary status and perform seismic analysis of MOST target: the star $\epsilon$ Eridani. We adopt the different input parameters to construct the models by fitting the available observational constraints: e.g., $T_{eff}$, $L$, $R$, $[Fe/H]$. From computation, we obtain the average large spacings of $\epsilon$ Eridani about $194\pm 1 \mu$Hz. The age of the diffused models has been found to be about 1 Gyr, which is younger than one determined previously by models without diffusion. We found that the effect of pure helium diffusion on the internal structure of the young low-mass star is slight, but the metal diffusion influence is obvious. The metal diffusion leads the models to have much higher temperature in the radiation interior, correspondingly the higher sound speed in the interior of the model, thereby the larger frequency and spacings.

Published
2008
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22. Reflections on the Developing Civil Service System in China

Author

Ruhai Li and Ning Gai

Subjects
Political science, Planned economy, Civil service, General Earth and Planetary Sciences, Public administration, China, Period (music), General Environmental Science
Abstract

In the 1980s. China began to implement a civil service system to establish a market-oriented economy and foster reform of the politico-administrative system. This modem civil service system was designed to replace the traditional ca personnel system, which, strictired around a centrally planned economy, originated during the period of China's revolutionary struggles. Focusing on this historical transition, this this article explores the relations that persist between the two systems and asks how and why the modem civil service system came into being at this time.

Published
2002
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23. Asteroseismic Diagram for Subgiants and Red Giants

Author

Peng Yu, Xianghua Dou, Yanke Tang, and Ning Gai

Subjects
Physics, 010308 nuclear & particles physics, Space and Planetary Science, 0103 physical sciences, Diagram, Astronomy and Astrophysics, Astrophysics, 010303 astronomy & astrophysics, 01 natural sciences
Published
2017
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24. Decreased serum obestatin consequent upon TRIB3 Q84R polymorphism exacerbates carotid atherosclerosis in subjects with metabolic syndrome

Author

Ze-Jun Song, Ke-Zhi Jia, Xiu-Hua Zhang, Yan-Li Yang, Ai-Dong Cui, and Ning-Ning Gai

Subjects
medicine.medical_specialty, business.industry, Research, Endocrinology, Diabetes and Metabolism, Confounding, TRIB3, Obestatin, medicine.disease, Metabolic syndrome, lcsh:Nutritional diseases. Deficiency diseases, Insulin resistance, Endocrinology, Carotid atherosclerosis, Internal medicine, Diabetes mellitus, Genotype, Internal Medicine, medicine, business, lcsh:RC620-627, Homeostasis
Abstract

Background Functional TRIB3 Q84R polymorphism has been associated with insulin resistance. Obestatin, improving insulin resistance, exerts obscure effects on metabolic syndrome (MetS) and carotid atherosclerosis. Aims to investigate whether the prevalent TRIB3 Q84R polymorphism has profound implications for alterations of serum obestatin and what effect obestatin exerts on carotid atherosclerosis. Methods A total of 518 unrelated Chinese subjects consisted of control (n = 258) and MetS (n = 260) groups. Clinical and biochemical characteristics were collected. The level of serum obestatin was measured. Genotype the functional TRIB3 Q84R polymorphism. All subjects underwent ultrasonography to determine carotid intima-media thickness (IMT). Results Serum obestatin was significantly decreased in MetS as compared with the control group (P = 0.042). Among the MetS group participants possessing RR84 genotype had significantly lower levels of serum obestatin than those with QQ84 or QR84 genotypes (P = 0.008, P = 0.043) with similar significant difference among the control group. Factorial analyses showed statistically significant interactions between MetS and RR84 genotype (P = 0.009 for interaction for obestatin). On correlation analysis, obestatin correlated negatively with homeostasis model assessment insulin resistance (r = -0.163, P = 0.010) and IMT (r = -0.256, P = 0.011). On partial analyses, obestatin negatively correlated with IMT(r = -0.259, P = 0.024) after controlling for the confounding factors. Conclusion MetS individuals with TRIB3 RR84 genotype demonstrated further decreased serum obestatin. Decreased serum obestatin might in part exacerbate insulin resistance and carotid atherosclerosis.

Published
2012
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25. Fundamental properties of five Kepler stars using global asteroseismic quantities and ground-based observations

Author

Rasmus Handberg, Karen Kinemuchi, Tiago L. Campante, Antonio Frasca, Jørgen Christensen-Dalsgaard, Hans Bruntt, Alfio Bonanno, Timothy R. White, D. Salabert, I. M. Brandão, Anwesh Mazumdar, Akshay Subramaniam, Savita Mathur, Sarbani Basu, Hans Kjeldsen, C. Régulo, O. L. Creevey, A. O. Thygesen, Jessie L. Christiansen, Jishnu Bhattacharya, K. Biazzo, Ning Gai, Ewa Niemczura, Juan Carlos Suárez, G. Doğan, Michael N. Fanelli, P.-O. Quirion, Tushar Shrotriya, J. Molenda-Żakowicz, Y. P. Elsworth, Christoffer Karoff, Mário J. P. F. G. Monteiro, Rafael A. García, William J. Chaplin, Timothy R. Bedding, S. G. Sousa, Dennis Stello, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Optical telescopes, Time series, Metallicity, FOS: Physical sciences, Astrophysics, 01 natural sciences, 7. Clean energy, Nordic Optical Telescope, Spectral line, Frequency separation, 0103 physical sciences, stars: atmospheres, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, stars: general, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Seismology, Physics, 010308 nuclear & particles physics, Asteroseismology, Astronomy and Astrophysics, Radius, Surface gravity, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Satellite, Astrophysics::Earth and Planetary Astrophysics, stars: fundamental parameters, stars: oscillations
Abstract

We present an asteroseismic study of the solar-like stars KIC 11395018, KIC 10273246, KIC 10920273, KIC 10339342, and KIC 11234888 using short-cadence time series of more than eight months from the Kepler satellite. For four of these stars, we derive atmospheric parameters from spectra acquired with the Nordic Optical Telescope. The global seismic quantities (average large frequency separation and frequency of maximum power), combined with the atmospheric parameters, yield the mean density and surface gravity with precisions of 2% and ~0.03 dex, respectively. We also determine the radius, mass, and age with precisions of 2-5%, 7-11%, and ~35%, respectively, using grid-based analyses. We determine asteroseismic distances to these stars with a precision better than 10%, and constrain the stellar inclination for three of the stars. An Li abundance analysis yields an independent estimate of the age, but this is inconsistent with the asteroseismically determined age for one of the stars. We compare the results from five different grid-based analyses, and we find that they all provide radius and mass values to within 2.4sigma. The absence of a metallicity constraint when the average large frequency separation is measured with a precision of 1% biases the fitted radius and mass for the stars with non-solar metallicity (metal-rich KIC 11395018 and metal-poor KIC 10273246), while including a metallicity constraint reduces the uncertainties in both of these parameters by almost a factor of two. We found that including the average small frequency separation improves the determination of the age only for KIC 11395018 and KIC 11234888, and for the latter this improvement was due to the lack of strong atmospheric constraints. (Abridged)., accepted A&A, 14 two-column pages + appendix, 5 figures, 15 tables

Published
2012
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26. Ensemble asteroseismology of solar-type stars with the NASA Kepler mission

Author

Mário J. P. F. G. Monteiro, Tiago L. Campante, L. Esch, William J. Borucki, M. D. Suran, Dennis Stello, Graham A. Verner, Travis S. Metcalfe, Jon M. Jenkins, Jørgen Christensen-Dalsgaard, Alfio Bonanno, Enrico Corsaro, William J. Chaplin, Andrea Miglio, D. Salabert, Savita Mathur, Orlagh Creevey, J. Van Cleve, Joanna Molenda-Żakowicz, I. M. Brandão, Daniel Huber, Steven J. Hale, Christoffer Karoff, Jérôme Ballot, G. Houdek, D. Pricopi, Aldo Serenelli, Rafael A. García, L. Girardi, Todd C. Klaus, Yvonne Elsworth, H. Bruntt, Patrick Gaulme, S. G. Sousa, Saskia Hekker, A.-M. Broomhall, Timothy R. Bedding, Roger New, P.-O. Quirion, Ian R. Stevens, Ning Gai, T. Appourchaux, Ronald L. Gilliland, V. Silva Aguirre, Michael Thompson, Sarbani Basu, Timothy R. White, S. D. Kawaler, Clara Régulo, Marc H. Pinsonneault, G. Doğan, K. Uytterhoeven, Timothy M. Brown, Anwesh Mazumdar, Hans Kjeldsen, Karen Kinemuchi, Rasmus Handberg, B. Mosser, Antonio Jiménez, School of Physics and Astronomy, University of Birmingham [Birmingham], Aarhus University [Aarhus], Yale University [New Haven], Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Sydney Institute for Astronomy (SIfA), The University of Sydney, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Space Telescope Science Institute (STSci), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), University of Vienna [Vienna], Iowa State University (ISU), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), University of Wrocław [Poland] (UWr), Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto = University of Porto, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Catania (OACT), Universidad de La Laguna [Tenerife - SP] (ULL), Instituto de Astrofisica de Canarias (IAC), Homi Bhabha National Institute (HBNI), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Materials and Engineering Research Institute [Sheffield] (MERI), Sheffield Hallam University, Ohio State University [Columbus] (OSU), Astronomical Institute of Romanian Academy, Romanian Academy, Canadian Space Agency (CSA), Institut d'Estudis Espacials de Catalunya (IEEC-CSIC), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, NASA Ames Research Center (ARC), Las Cumbres Observatory (LCO), Low Energy Astrophysics (API, FNWI), Stellar Astrophysics Centre [Aarhus] (SAC), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Universidade do Porto, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Faculdade de Ciências

Subjects
Astronomia, Física, Física [Ciências exactas e naturais], 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Asteroseismology, Kepler Input Catalog, Kepler-47, Physical sciences [Natural sciences], Astronomy, Physical sciences, Stellar dynamics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Kepler-62, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Multidisciplinary, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Stellar collision, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Exoplanet, Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Kepler-62c
Abstract

In addition to its search for extra-solar planets, the NASA Kepler Mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solartype stars in the Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius and age) and to test theories of stellar evolution. We find that the distribution of observed masses of these stars shows intriguing differences to predictions from models of synthetic stellar populations in the Galaxy., 20 pages, including on-line supporting material

Published
2011
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27. Sounding open clusters: Asteroseismic constraints from kepler on the properties of NGC6791 and NGC6819

Author

Sarbani Basu, Frank Grundahl, Dennis Stello, Thomas Kallinger, Saskia Hekker, Benoit Mosser, Rafael A. García, Savita Mathur, Karsten Brogaard, Hans Bruntt, William J. Chaplin, Ning Gai, Yvonne Elsworth, Lisa Esch, Jerome Ballot, Timothy R. Bedding, Michael Gruberbauer, Daniel Huber, Andrea Miglio, Mutlu Yildiz, Hans Kjeldsen, Jørgen Christensen-Dalsgaard, Ronald L. Gilliland, Michael M. Fanelli, Khadeejah A. Ibrahim, Jeffrey C. Smith, Ege Üniversitesi, Department of Astronomy, Yale University, Danish AsteroSeismology Centre (DASC), Sydney Institute for Astronomy (SIfA), Department of Physics and Astronomy, University of British Columbia, School of Physics and Astronomy, University of Birmingham, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Pôle Planétologie du LESIA, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), High Altitude Observatory, National Center for Atmospheric Research, Department of Astronomy, Beijing Normal University, Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institute for Computational Astrophysics, Department of Astronomy and Physics, Saint Marys University, Institut d'Astrophysique, Géophysique et Océanographie, Université de Liège, Department of Astronomy and Space Sciences, Ege University, Space Telescope Science Institute (STScI), Bay Area Environmental Research Institute/NASA Ames Research Center, Moffett Field, Orbital Sciences Corporation, NASA Ames Research Center, Moffett Field, and SETI Institute, NASA Ames Research Center, Moffett Field

Subjects
Physics, FOS: Physical sciences, Astronomy and Astrophysics, Radius, Astrophysics, stars: interiors, Kepler, open clusters and associations: individual (NGC 6819: NGC 6791), Distance modulus, Stars, Depth sounding, Cover (topology), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, open clusters and associations: individual (NGC 6819, NGC 6791), stars: fundamental parameters, stars: oscillations, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Solar and Stellar Astrophysics (astro-ph.SR), Open cluster
Abstract

WOS: 000287194100010, We present initial results on some of the properties of open clusters NGC 6791 and NGC 6819 derived from asteroseismic data obtained by NASA's Kepler mission. In addition to estimating the mass, radius, and log g of stars on the red giant branch (RGB) of these clusters, we estimate the distance to the clusters and their ages. Our model-independent estimate of the distance modulus of NGC 6791 is (m - M)(0) = 13.11 +/- 0.06. We find (m - M)(0) = 11.85 +/- 0.05 for NGC 6819. The average mass of stars on the RGB of NGC 6791 is 1.20 +/- 0.01 M-circle dot, while that of NGC 6819 is 1.68 +/- 0.03 M-circle dot. It should be noted that we do not have data that cover the entire RGB and the actual mass will be somewhat lower. We have determined model-dependent estimates of ages of these clusters. We find ages between 6.8 and 8.6 Gyr for NGC 6791, however, most sets of models give ages around 7 Gyr. We obtain ages between 2 and 2.4 Gyr for NGC 6819., NASA's Science Mission Directorate; Science and Technology Facilities CouncilScience & Technology Facilities Council (STFC) [ST/F002041/1], Funding for the Kepler mission is provided by NASA's Science Mission Directorate. The authors wish to thank the entire Kepler team, without whom these results would not be possible. We also thank all funding councils and agencies that have supported the activities of Working Group 2 of the Kepler Asteroseismic Science Consortium.

Published
2011
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28. Predicting the detectability of oscillations in solar-type stars observed by Kepler

Author

T. Appourchaux, Mário J. P. F. G. Monteiro, R. L. Gilliland, Tiago L. Campante, David G. Koch, Jørgen Christensen-Dalsgaard, J. M. Jenkins, Clara Régulo, A.-M. Broomhall, Marc H. Pinsonneault, B. Mosser, Michael Thompson, D. Pricopi, Alfio Bonanno, T. S. Metcalfe, Christoffer Karoff, Jessie L. Christiansen, B. D. Clarke, Hans Kjeldsen, Todd C. Klaus, William J. Borucki, Rasmus Handberg, Steven D. Kawaler, Graham A. Verner, L. Esch, D. Salabert, Timothy M. Brown, Sarbani Basu, Ning Gai, Timothy R. Bedding, O. L. Creevey, G. Houdek, Patrick Gaulme, Saskia Hekker, S. T. Bryson, Dennis Stello, Roger New, P.-O. Quirion, Yvonne Elsworth, J. Molenda-Zakowicz, Natalie M. Batalha, Daniel Huber, Savita Mathur, Enrico Corsaro, William J. Chaplin, Jérôme Ballot, Steven J. Hale, Rafael A. García, M. D. Suran, Deokkeun An, O. Benomar, Ian W. Roxburgh, School of Physics and Astronomy, University of Birmingham, Danish AsteroSeismology Centre (DASC), Sydney Institute for Astronomy (SIfA), Space Telescope Science Institute (STScI), Department of Physics and Astronomy, Iowa State University, Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut für Astronomie, Universität Wien (IfA), High Altitude Observatory, National Center for Atmospheric Research, Astronomical Institute, University of Wroclaw, Centro de Astrofísica, Universidade do Porto, National Aeronautics and Space Administration, Ames Research Center, Las Cumbres Observatory, Goleta, SETI Institute, NASA Ames Research Center, Moffett Field, Orbital Sciences Corporation, NASA Ames Research Center, Moffett Field, Department of Science Education, Ewha Womans University, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Department of Astronomy, Yale University, INAF-Osservatorio Astrofisico di Catania (INAF-OACt), Universidad de La Laguna [Tenerife - SP] (ULL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Materials Engineering Research Institute, Faculty of Arts, Computing, Engineering and Sciences, Sheffield Hallam University, Department of Astronomy, Ohio State University, Astronomical Institute of the Romanian Academy, Bucharest, Canadian Space Agency (CSA), Instituto de Astrofísica de Canarias (IAC), Astronomy Unit, Queen Mary, and Low Energy Astrophysics (API, FNWI)

Subjects
Physics, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Radius, Type (model theory), Kepler, Asteroseismology, Exoplanet, Stars, Apparent magnitude, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Asteroseismology of solar-type stars has an important part to play in the exoplanet program of the NASA Kepler Mission. Precise and accurate inferences on the stellar properties that are made possible by the seismic data allow very tight constraints to be placed on the exoplanetary systems. Here, we outline how to make an estimate of the detectability of solar-like oscillations in any given Kepler target, using rough estimates of the temperature and radius, and the Kepler apparent magnitude., Comment: 21 pages, 6 figures, accepted for publication Astrophysical Journal

Published
2011
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29. Detection of Solar-like Oscillations from Kepler Photometry of the Open Cluster NGC 6819

Author

Yveline Lebreton, Charles S. Baldner, Jørgen Christensen-Dalsgaard, Juan Carlos Suárez, Andrea Miglio, J. Molenda-Zakowicz, Nada Jevtic, Achim Weiss, Savita Mathur, Marie-Jo Goupil, L. Esch, Saskia Hekker, William J. Borucki, Caroline Barban, Hans Bruntt, Rafael A. García, Daniel Huber, Aldo Serenelli, Ian R. Stevens, Victor Silva Aguirre, Frank Grundah, Vinothini Sangaralingam, Katia Biazzo, Hans Kjeldsen, Torben Arentoft, Christiaan Sterken, Søren Meibom, Ian W. Roxburgh, Jérôme Ballot, Yvonne Elsworth, Karsten Brogaard, Francesca D'Antona, Dennis Stello, Ning Gai, Josefina Montalbán, Christoffer Karoff, Biwei Jiang, Timothy R. Bedding, Sarbani Basu, William J. Chaplin, Ronald L. Gilliland, Timothy M. Brown, B. Mosser, Kevin Belkacem, Róbert Szabó, Jon M. Jenkins, Pierre Demarque, Arlette Noels, Teodoro Roca Cortés, Peter Stine, Reza Samadi, David G. Koch, Sydney Institute for Astronomy (SIfA), The University of Sydney, Department of Astronomy, Yale University [New Haven], Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), School of Physics and Astronomy, University of Birmingham [Birmingham], Las Cumbres Observatory Global Telescope, Danish AsteroSeismology Centre (DASC), Aarhus University [Aarhus], Space Telescope Science Institute (STSci), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Indian Institute of Astrophysics (IIA), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Département des Sciences et Gestion de l'Environnement/Océanologie [Liège], Université de Liège, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), INAF - Osservatorio Astronomico di Roma (OAR), Beijing Normal University (BNU), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Engineering Technology, Bloomsburg University, Astronomical Institute [Wroclaw], University of Wrocław [Poland] (UWr), Instituto de Astrofisica de Canarias (IAC), Departmento de Astrofísica, Universidad de La Laguna [Tenerife - SP] (ULL), Department of Computer Science (Queen Mary University of London), Queen Mary University of London (QMUL), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Vrije Universiteit Brussel (VUB), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), NASA Ames Research Center (ARC), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Beijing Normal University, University of Wrocław [Poland], Vrije Universiteit [Brussels] (VUB), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Harvard University-Smithsonian Institution, and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: interiors, 01 natural sciences, Asteroseismology, Luminosity, open clusters and associations: individual: NGC 6819, techniques: photometric, Frequency separation, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Solar-like oscillations, 010303 astronomy & astrophysics, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Radial velocity, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, stars: fundamental parameters, stars: oscillations, Open cluster
Abstract

Asteroseismology of stars in clusters has been a long-sought goal because the assumption of a common age, distance and initial chemical composition allows strong tests of the theory of stellar evolution. We report results from the first 34 days of science data from the Kepler Mission for the open cluster NGC 6819 -- one of four clusters in the field of view. We obtain the first clear detections of solar-like oscillations in the cluster red giants and are able to measure the large frequency separation and the frequency of maximum oscillation power. We find that the asteroseismic parameters allow us to test cluster-membership of the stars, and even with the limited seismic data in hand, we can already identify four possible non-members despite their having a better than 80% membership probability from radial velocity measurements. We are also able to determine the oscillation amplitudes for stars that span about two orders of magnitude in luminosity and find good agreement with the prediction that oscillation amplitudes scale as the luminosity to the power of 0.7. These early results demonstrate the unique potential of asteroseismology of the stellar clusters observed by Kepler., Comment: 5 pages, 4 figures, accepted by ApJ (Lett.)

Published
2010
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30. A PRECISE ASTEROSEISMIC AGE AND RADIUS FOR THE EVOLVED SUN-LIKE STAR KIC 11026764

Author

V. Silva Aguirre, Graham A. Verner, David G. Koch, J. Molenda-Zakowicz, O. L. Creevey, P. Eggenberger, William J. Chaplin, Daniel Huber, Savita Mathur, S. Frandsen, A.-M. Broomhall, T. S. Metcalfe, Tiago L. Campante, Stephen T. Fletcher, Michael Thompson, Antonio Frasca, Roger New, Alfio Bonanno, P.-O. Quirion, Rasmus Handberg, M. Di Mauro, I. N. Kitiashvili, D. Salabert, Jesper Schou, Timothy M. Brown, Timothy R. White, K. H. Sato, Timothy R. Bedding, S. Dreizler, Rafael A. García, Jørgen Christensen-Dalsgaard, Saskia Hekker, Juan Carlos Suárez, L. Esch, A. Moya, Hans Kjeldsen, Paul Wilson, J. P. Marques, Thierry Appourchaux, Clara Régulo, Yvonne Elsworth, Dennis Stello, G. Doğan, J. Ballot, Sarbani Basu, William J. Borucki, Jon M. Jenkins, R. L. Gilliland, Christoffer Karoff, Katia Biazzo, Alexander G. Kosovichev, S. G. Sousa, Ian W. Roxburgh, Ning Gai, M. Bazot, L. Piau, Mário J. P. F. G. Monteiro, H. Bruntt, Faculdade de Ciências, High Altitude Observatory, National Center for Atmospheric Research, Centro de Astrofísica, Universidade do Porto, University of Sheffield [Sheffield], Astronomical Institute, University of Wroclaw, Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), School of Physics and Astronomy, University of Birmingham, Danish AsteroSeismology Centre (DASC), Observatoire Astronomique de l'Université de Genève, Sydney Institute for Astronomy (SIfA), Observatoire de Paris, Université Paris sciences et lettres (PSL), Instituto de Astrofísica de Canarias (IAC), Canadian Space Agency (CSA), INAF-Osservatorio Astrofisico di Catania (INAF-OACt), Max-Planck-Institut für Astrophysik (MPA), Department of Astronomy, Yale University, Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF-Roma), HEPL, Stanford University, Stanford, Center for Turbulence Research, Stanford University, Instituto de Astrofisica de Andalucia, CSIC (IAA), Laboratorio de Astrofísica, CAB (CSIC-INTA), Villanueva de la Cañada, Madrid, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), INAF-Osservatorio Astrofisico di Arcetri (INAF-OAA), Institut für Astrophysik, Universität Göttingen, Nordic Optical Telescope, Las Cumbres Observatory, Goleta, Space Telescope Science Institute (STScI), Materials Engineering Research Institute, Sheffield Hallam University, Sheffield, Astronomy Unit, Queen Mary, Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), National Aeronautics and Space Administration, Ames Research Center, and SETI Institute, NASA Ames Research Center, Moffett Field

Subjects
Astronomia, Física, Física [Ciências exactas e naturais], FOS: Physical sciences, Astrophysics, Star (graph theory), 01 natural sciences, Physical sciences [Natural sciences], Planet, Astronomy, Physical sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Earth and Planetary Astrophysics (astro-ph.EP), 010308 nuclear & particles physics, Oscillation, Subgiant, Astronomy and Astrophysics, Radius, Exoplanet, Stars, Photometry (astronomy), Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract

The primary science goal of the Kepler Mission is to provide a census of exoplanets in the solar neighborhood, including the identification and characterization of habitable Earth-like planets. The asteroseismic capabilities of the mission are being used to determine precise radii and ages for the target stars from their solar-like oscillations. Chaplin et al. (2010) published observations of three bright G-type stars, which were monitored during the first 33.5 days of science operations. One of these stars, the subgiant KIC 11026764, exhibits a characteristic pattern of oscillation frequencies suggesting that it has evolved significantly. We have derived asteroseismic estimates of the properties of KIC 11026764 from Kepler photometry combined with ground-based spectroscopic data. We present the results of detailed modeling for this star, employing a variety of independent codes and analyses that attempt to match the asteroseismic and spectroscopic constraints simultaneously. We determine both the radius and the age of KIC 11026764 with a precision near 1%, and an accuracy near 2% for the radius and 15% for the age. Continued observations of this star promise to reveal additional oscillation frequencies that will further improve the determination of its fundamental properties., Comment: 16 pages, 6 figures, 4 tables, ApJ in press

Published
2010
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31. ASTEROSEISMIC ANALYSIS OF THE INTERNAL STRUCTURE AND EVOLUTION OF RED GIANT BRANCH BUMP STARS

Author

Ning Gai and Yanke Tang

Subjects
Convection, Physics, Metallicity, chemistry.chemical_element, Astronomy and Astrophysics, Astrophysics, Red-giant branch, Stars, chemistry, Space and Planetary Science, Speed of sound, Ionization, Astrophysics::Solar and Stellar Astrophysics, Adiabatic process, Astrophysics::Galaxy Astrophysics, Helium
Abstract

The "bump" is a prominent feature of the red giant branch (RGB) luminosity function of stellar clusters. Through constructing a grid of models with different masses and metallicities to study the feature of the RGB bump luminosity we find that the luminosity increases almost monotonically with increasing mass for a given metallicity and decreases monotonically with increasing metallicity. Moreover, different stars have different shapes of the RGB bump. It is correlated with the sharpness of the H discontinuity, which is left over by the convection envelope during the first dredge-up. Using the periodicity in the small separations d(01), d(10) to probe the internal structure, we find that, at about half the acoustic radius, the sound speed has a sharp variation that is caused by a local depression of the first adiabatic exponent Gamma(1) in the second helium ionization zone. It induces an oscillation modulation in d(01), d(10) with a period of 6.4 mu Hz. Meanwhile, in the same model, the base of the convective envelope is located at a relatively small acoustic radius t(envp)/T, which is about 10(-1). It is too deep to detect the exact location of the bottom of the outer convective envelope. In order to discriminate the evolutionary status of different stars, we calculate the asymptotic g-mode period spacing Delta Pi(1). We find that Delta Pi(1) decreases monotonically with evolution. It is a reliable parameter for distinguishing stars in different positions of the RGB bump.

Published
2015
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32. AN IN-DEPTH STUDY OF GRID-BASED ASTEROSEISMIC ANALYSIS

Author

Ning Gai, Sarbani Basu, William J. Chaplin, and Yvonne Elsworth

Subjects
Physics, Metallicity, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Radius, Grid, Grid based, Kepler, Stars, Star cluster, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Cluster (physics), Astrophysics::Earth and Planetary Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

NASA's Kepler mission is providing basic asteroseismic data for hundreds of stars. One of the more common ways of determining stellar characteristics from these data is by so-called "grid based" modelling. We have made a detailed study of grid-based analysis techniques to study the errors (and error-correlations) involved. As had been reported earlier, we find that it is relatively easy to get very precise values of stellar radii using grid-based techniques. However, we find that there are small, but significant, biases that can result because of the grid of models used. The biases can be minimized if metallicity is known. Masses cannot be determined as precisely as the radii, and suffer from larger systematic effects. We also find that the errors in mass and radius are correlated. A positive consequence of this correlation is that log g can be determined both precisely and accurately with almost no systematic biases. Radii and log g can be determined with almost no model dependence to within 5% for realistic estimates of error in asteroseismic and conventional observations. Errors in mass can be somewhat higher unless accurate metallicity estimates are available. Age estimates of individual stars are the most model dependent. The errors are larger too. However, we find that for star-clusters, it is possible to get a relatively precise age if one assumes that all stars in a given cluster have the same age., Comment: ApJ, in press

Published
2011
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33. Asteroseismic modelling of the metal-poor starτCeti

Author

Yanke Tang and Ning Gai

Subjects
Physics, Hertzsprung–Russell diagram, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Effective temperature, Asteroseismology, Luminosity, Stars, symbols.namesake, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, symbols, Astrophysics::Solar and Stellar Astrophysics, Stellar structure, Astrophysics::Earth and Planetary Astrophysics, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Stellar pulsation
Abstract

Context. Asteroseismology is an effcient tool not only for testing stellar structure and evolutionary theory but also constraining the parameters of stars for which solar-like oscillations are detected, presently. As an important southern asteroseismic target, Tau Ceti, is a metal-poor star. The main features of the oscillations and some frequencies of ? Ceti have been identified. Many scientists propose to comprehensively observe this star as part of the Stellar Observations Network Group. Aims. Our goal is to obtain the optimal model and reliable fundamental parameters for the metal-poor star Tau Ceti by combining all non-asteroseismic observations with these seismological data. Methods. Using the Yale stellar evolution code (YREC), a grid of stellar model candidates that fall within all the error boxes in the HR diagram have been constructed, and both the model frequencies and large- and small- frequency separations are calculated using the Guenther's stellar pulsation code. The \chi2c minimization is performed to identify the optimal modelling parameters that reproduce the observations within their errors. The frequency corrections of near-surface effects to the calculated frequencies using the empirical law, as proposed by Kjeldsen and coworkers, are applied to the models. Results. We derive optimal models, corresponding to masses of about 0.775 - 0.785 M? and ages of about 8 - 10 Gyr. Furthermore, we find that the quantities derived from the non-asteroseismic observations (effective temperature and luminosity) acquired spectroscopically are more accurate than those inferred from interferometry for ? Ceti, because our optimal models are in the error boxes B and C, which are derived from spectroscopy results., Comment: 8 pages, 5 figures, accepted by A&A

Published
2010
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34. Decreased serum obestatin consequent upon TRIB3 Q84R polymorphism exacerbates carotid atherosclerosis in subjects with metabolic syndrome.

Author

Ai-dong Cui, Ning-ning Gai, Xiu-hua Zhang, Ke-zhi Jia, Yan-li Yang, and Ze-jun Song

Subjects
*GENETIC polymorphisms, *GENETIC research, *DRUG resistance, *INSULIN resistance, *ATHEROSCLEROSIS
Abstract

Background: Functional TRIB3 Q84R polymorphism has been associated with insulin resistance. Obestatin, improving insulin resistance, exerts obscure effects on metabolic syndrome (MetS) and carotid atherosclerosis. Aims to investigate whether the prevalent TRIB3 Q84R polymorphism has profound implications for alterations of serum obestatin and what effect obestatin exerts on carotid atherosclerosis. Methods: A total of 518 unrelated Chinese subjects consisted of control (n = 258) and MetS (n = 260) groups. Clinical and biochemical characteristics were collected. The level of serum obestatin was measured. Genotype the functional TRIB3 Q84R polymorphism. All subjects underwent ultrasonography to determine carotid intima-media thickness (IMT). Results: Serum obestatin was significantly decreased in MetS as compared with the control group (P = 0.042). Among the MetS group participants possessing RR84 genotype had significantly lower levels of serum obestatin than those with QQ84 or QR84 genotypes (P = 0.008, P = 0.043) with similar significant difference among the control group. Factorial analyses showed statistically significant interactions between MetS and RR84 genotype (P = 0.009 for interaction for obestatin). On correlation analysis, obestatin correlated negatively with homeostasis model assessment insulin resistance (r = -0.163, P = 0.010) and IMT (r = -0.256, P = 0.011). On partial analyses, obestatin negatively correlated with IMT(r = -0.259, P = 0.024) after controlling for the confounding factors. Conclusion: MetS individuals with TRIB3 RR84 genotype demonstrated further decreased serum obestatin. Decreased serum obestatin might in part exacerbate insulin resistance and carotid atherosclerosis. [ABSTRACT FROM AUTHOR]

Published
2012
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35. Asteroseismic Investigations of the Binary System HD 176465.

Author

Ning Gai, Sarbani Basu, and Yanke Tang

Subjects
*INTERIOR of stars, *STELLAR oscillations, *RADIAL velocity of stars, *INTERSTELLAR medium, *SOLAR activity
Abstract

HD 176465 is a binary system for which both components are solar-like pulsators and oscillation frequencies were observed by the Kepler mission. In this paper, we have modeled the asteroseismic and spectroscopic data of the stars, and have determined their convection-zone helium abundances using the signatures left by the He ii ionization zone on the mode frequencies. As expected, we find that the components of the binary are of the same age within uncertainties (3.087 ± 0.580 Gyr and 3.569 ± 0.912 Gyr); they also have the same initial helium abundance (Yinit = 0.253 ± 0.006 and 0.254 ± 0.008). Their current metallicity ([Fe/H] = −0.275 ± 0.04 and −0.285 ± 0.04) is also the same within errors. Fits to the signature of the He ii acoustic glitch yield current helium abundances of YA = 0.224 ± 0.006 and YB = 0.233 ± 0.008 for the two components. Analyzing the complete ensemble of models generated for this investigation, we find that both the amplitude and acoustic depth of the glitch signature arising from the second helium ionization zone and the base of the convection zone (CZ) are functions of mass. We show that the acoustic depths of these glitches are positively correlated with each other. The analysis can help us to detect the internal structure and constrain the chemical compositions. [ABSTRACT FROM AUTHOR]

Published
2018
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36. Asteroseismic Diagram for Subgiants and Red Giants.

Author

Ning Gai, Yanke Tang, Peng Yu, and Xianghua Dou

Subjects
*ASTEROSEISMOLOGY, *STELLAR parallax, *RED giants, *STELLAR mass, *EIGENFREQUENCIES
Abstract

Asteroseismology is a powerful tool for constraining stellar parameters. NASA’s Kepler mission is providing individual eigenfrequencies for a huge number of stars, including thousands of red giants. Besides the frequencies of acoustic modes, an important breakthrough of the Kepler mission is the detection of nonradial gravity-dominated mixed-mode oscillations in red giants. Unlike pure acoustic modes, mixed modes probe deeply into the interior of stars, allowing the stellar core properties and evolution of stars to be derived. In this work, using the gravity-mode period spacing and the large frequency separation, we construct the ΔΠ1–Δν asteroseismic diagram from models of subgiants and red giants with various masses and metallicities. The relationship ΔΠ1–Δν is able to constrain the ages and masses of the subgiants. Meanwhile, for red giants with masses above 1.5 M⊙, the ΔΠ1–Δν asteroseismic diagram can also work well to constrain the stellar age and mass. Additionally, we calculate the relative “isochrones” τ, which indicate similar evolution states especially for similar mass stars, on the ΔΠ1–Δν diagram. [ABSTRACT FROM AUTHOR]

Published
2017
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