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Data and analysis methodology used for the SDSS/APOGEE Data Releases 13 and 14 are described, highlighting differences from the DR12 analysis presented in Holtzman (2015). Some improvement in the handling of telluric absorption and…

Innovation in the ground and space-based instruments has taken us into a new age of spectroscopy, in which a large amount of stellar content is becoming available. So, automatic classification of stellar spectra became subjective in recent…

Solar and Stellar Astrophysics · Physics 2020-06-26 Y. A. Azzam , M. I. Nouh , A. A. Shaker

The accuracy of the estimated stellar atmospheric parameter decreases evidently with the decreasing of spectral signal-to-noise ratio (SNR) and there are a huge amount of this kind observations, especially in case of SNR$<$30. Therefore, it…

Astrophysics of Galaxies · Physics 2023-12-27 Xiangru Li , Zhu Wang , Si Zeng , Caixiu Liao , Bing Du , X. Kong , Haining Li

As a typical data-driven method, deep learning becomes a natural choice for analysing astronomical data nowadays. In this study, we built a deep convolutional neural network to estimate basic stellar parameters $T\rm{_{eff}}$, log g,…

Astrophysics of Galaxies · Physics 2022-08-03 Zhuohan Li , Gang Zhao , Yuqin Chen , Xilong Liang , Jingkun Zhao

We report the first detailed chemical abundance analysis of the exoplanet-hosting M-dwarf stars Kepler-138 and Kepler-186 from the analysis of high-resolution ($R$ $\sim$ 22,500) $H$-band spectra from the SDSS IV - APOGEE survey. Chemical…

We present K band spectra for 133 nearby (d < 33 parsecs) M dwarfs, including 18 M dwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 M dwarf planet hosts, more than 2/3 of the M dwarfs in the Northern 8…

Solar and Stellar Astrophysics · Physics 2012-03-15 Bárbara Rojas-Ayala , Kevin R. Covey , Philip S. Muirhead , James P. Lloyd

Aims:To support the computation and evolutionary interpretation of periods associated with the rotational modulation, oscillations, and variability of stars located in the CoRoT fields, we are conducting a spectroscopic survey for stars…

We use time-domain optical spectroscopy to distinguish between broad emission lines powered by accreting black holes (BHs) or stellar processes (i.e., supernovae) for 16 galaxies identified as AGN candidates by Reines \etal (2013). Our…

Deep learning with artificial neural networks is increasingly gaining attention, because of its potential for data-driven astronomy. However, this methodology usually does not provide uncertainties and does not deal with incompleteness and…

Astrophysics of Galaxies · Physics 2019-01-11 Henry W. Leung , Jo Bovy

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) - one of the Sloan Digital Sky Survey III programs -- is using near-infrared spectra of $\sim 100,000$ red giant branch star candidates to study the structure of the Milky…

In this study, the fundamental stellar atmospheric parameters (Teff, log g, [Fe/H] and [{\alpha}/Fe]) were derived for low-resolution spectroscopy from LAMOST DR5 with Generative Spectrum Networks (GSN). This follows the same scheme as a…

Instrumentation and Methods for Astrophysics · Physics 2019-01-23 Wang Rui , Luo A-li , Zhang Shuo , Hou Wen , Du Bing , Song Yi-Han , Wu Ke-Fei , Chen Jian-Jun , Zuo Fang , Qin Li , Chen Xiang-Lei , Lu Yan

Context: The abundances of the $\alpha$-elements are key for understanding the early chemical enrichment of the Galactic bulge. The elements of interest present lines in different wavelength regions, and some of them show lines only in part…

Solar and Stellar Astrophysics · Physics 2024-05-13 Patrícia da Silva , B. Barbuy , H. Ernandes , S. O. Souza , J. G. Fernández-Trincado , D. González-Díaz

M-dwarfs are emerging in the literature as promising targets for detecting low-mass, Earth-like planets. An important step in this process is to determine the stellar parameters of the M-dwarf host star as accurately as possible. Different…

Solar and Stellar Astrophysics · Physics 2015-05-20 I. Bozhinova , Ch. Helling , A. Scholz

We present follow-up SCExAO/CHARIS $H$ and $K$-band (R $\sim$ 70) high-contrast integral field spectroscopy and Keck/NIRC2 photometry of directly-imaged brown dwarf companion HD 33632 Ab and new radial-velocity data for the system from the…

This article investigates the problem of estimating stellar atmospheric parameters from spectra. Feature extraction is a key procedure in estimating stellar parameters automatically. We propose a scheme for spectral feature extraction and…

Instrumentation and Methods for Astrophysics · Physics 2015-08-04 Tan Yang , Xiangru Li

Context. As increasingly more spectroscopic data are being delivered by medium- and high-resolving power multi-object spectrographs, more automatic stellar parameter determination softwares are being developed. The quality of the spectra…

Solar and Stellar Astrophysics · Physics 2012-09-04 Helene Posbic , David Katz , Elisabetta Caffau , Piercarlo Bonifacio , Ana Gomez , Luca Sbordone , Frederic Arenou

Context. The APOGEE survey has obtained high-resolution infrared spectra of more than 100,000 stars. Deriving chemical abundances patterns of these stars is paramount to piecing together the structure of the Milky Way. While the derived…

Astrophysics of Galaxies · Physics 2016-10-12 Keith Hawkins , Thomas Masseron , Paula Jofre , Gerry Gilmore , Yvonne Elsworth , Saskia Hekker

Despite their large number in the Galaxy, M dwarfs remain elusive objects and the modeling of their photospheres has long remained a challenge (molecular opacities, dust cloud formation). Our objectives are to validate the BT-Settl model…

Solar and Stellar Astrophysics · Physics 2015-06-15 A. S. Rajpurohit , C. Reylé , F. Allard , D. Homeier , M. Schultheis , M. S. Bessell , A. C. Robin

The MaNGA Stellar Library (MaStar) is a large collection of high-quality empirical stellar spectra designed to cover all spectral types and ideal for use in the stellar population analysis of galaxies observed in the Mapping Nearby Galaxies…

Molecular bands of metal oxides and hydrides dominate the optical and near-infrared spectra of M dwarfs. High-resolution spectra of these bands have immense potential for determining many properties of these stars, such as effective…

Solar and Stellar Astrophysics · Physics 2023-11-29 P. Crozet , J. Morin , A. J. Ross , S. Bellotti , J. F. Donati , P. Fouqué , C. Moutou , P. Petit , A. Carmona , A. Kóspál , A. G. Adam , D. W. Tokaryk
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