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Related papers: A high resolution spectroscopic atlas of M subdwar…

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We define an enhanced spectral classification scheme for M dwarf stars, and use it to derive spectral classification of 104 northern stars with proper motions larger than 0.5"/yr which we discovered in a survey of high proper motion stars…

Astrophysics · Physics 2009-11-07 Sebastien Lepine , R. Michael Rich , Michael M. Shara

Analysis of initial observations from near-infrared sky surveys has shown that the resulting photometric catalogues, combined with far-red optical data, provide an extremely effective method of finding isolated, very low-temperature objects…

With the dual aims of enlarging the list of extremely metal-poor stars identified in the Galaxy, and boosting the numbers of moderately metal-deficient stars in directions that sample the rotational properties of the thick disk, we have…

We describe a technique for deriving effective temperatures, surface gravities, rotation velocities, and radial velocities from high resolution near-IR spectra. The technique matches the observed near-IR spectra to spectra synthesized from…

Astrophysics · Physics 2009-11-10 G. W. Doppmann , D. T. Jaffe

Ultracool dwarf stars and brown dwarfs provide a unique probe of large-scale Galactic structure and evolution; however, until recently spectroscopic samples of sufficient size, depth, and fidelity have been unavailable. Here, we present the…

We propose a revision of the system developed by L'epine et al. (2007) for spectroscopic M subdwarf classification. Based on an analysis of subdwarf spectra and templates from Savcheva et al. (2014), we show thatthe CaH1 feature originally…

Solar and Stellar Astrophysics · Physics 2019-11-20 Shuo Zhang , A-Li Luo , Georges Comte , John E. Gizis , Rui Wang , Yinbi Li , Li Qin , Xiao Kong , Yu Bai , Zhenping Yi

We present a 20-pc, volume-limited sample of M7-L8 dwarfs created through spectroscopic follow-up of sources selected from the Two Micron All Sky Survey (2MASS) Second Incremental Release Point Source Catalog. In this paper, we present…

Carbon and oxygen abundances of eight late M dwarfs are determined based on the near IR spectra of medium resolution. Seven objects with T_eff above 2600K are analyzed with the dust-free models. The M8.5 dwarf 2MASSI J1835379+325954 whose…

Solar and Stellar Astrophysics · Physics 2016-01-20 Takashi Tsuji , Tadashi Nakajima

Transit spectroscopy of terrestrial planets around nearby M dwarfs is a primary goal of space missions in coming decades. 3-D climate modeling has shown that slow-synchronous rotating terrestrial planets may develop thick clouds at the…

We present here quantitative diagnostic tools for cool giants that employ low-resolution near-infrared spectroscopy in the $K$-band for stellar population studies. In this study, a total of 260 cool giants (177 stars observed with X-shooter…

Solar and Stellar Astrophysics · Physics 2021-01-06 Supriyo Ghosh , D. K. Ojha , J. P. Ninan

M star spectra, at wavelengths beyond 1.35 $\mu$m, are dominated by water vapour yet terrestrial water vapour makes it notoriously difficult to make accurate measurement from ground-based observations. We have used the short wavelength…

Astrophysics · Physics 2009-11-07 Hugh R. A. Jones , Yakiv Pavlenko , Serena Viti , Jonathan Tennyson

Applying the revised M subdwarf classification criteria discussed in Paper I to LAMOST DR7, combining the M subdwarf sample from Savcheva et al, a new M subdwarf sample was constructed for further study. The atmospheric parameters for each…

Solar and Stellar Astrophysics · Physics 2021-02-24 Shuo Zhang , A-Li Luo , Georges Comte , Rui Wang , Yinbi Li , Bing Du , Wen Hou , Li Qin , John Gizis , Jian-Jun Chen , Xiang-Lei Chen , Yan Lu , Yi-Han Song , Hua-Wei Zhang , Fang Zuo

We compare high resolution infrared observations of the CO 3-1 bands in the 2.297-2.310 micron region of M dwarfs and one L dwarf with theoretical expectations. We find a good match between the observational and synthetic spectra throughout…

Brown dwarf spectra offer vital testbeds for our understanding of the chemical and physical processes that sculpt substellar atmospheres. Recently, atmospheric retrieval approaches have been applied to a number of low-resolution (R~100)…

Solar and Stellar Astrophysics · Physics 2023-07-12 Callie E. Hood , Jonathan J. Fortney , Michael R. Line , Jacqueline K. Faherty

Evolutionary and atmospheric models have become available for young ultralow-mass objects. These models are being used to determine fundamental parameters from observational properties. TiO bands are used to determine effective temperatures…

Astrophysics · Physics 2009-11-11 Ansgar Reiners

A new grid of detailed atmosphere model spectra for hot and moderately cool subdwarf stars is presented. High-resolution spectra and synthetic photometry are calculated in the range from 1000{\AA} to 10,000{\AA} using Non-LTE fully…

Solar and Stellar Astrophysics · Physics 2021-10-07 Thayse A. Pacheco , Marcos P. Diaz , Ronaldo S. Levenhagen , Paula R. T. Coelho

We present 10 - 19 um moderate resolution spectra of ten M dwarfs, one L dwarf, and two T dwarf systems obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. The IRS allows us to examine molecular spectroscopic…

Bayesian atmospheric retrieval tools can place constraints on the properties of brown dwarfs and hot Jupiters atmospheres. To fully exploit these methods, high signal-to-noise spectral libraries with well-understood uncertainties are…

We present interferometric diameter measurements of 21 K- and M- dwarfs made with the CHARA Array. This sample is enhanced by literature radii measurements to form a data set of 33 K-M dwarfs with diameters measured to better than 5%. For…