Mon. Not. R. Astron. Soc., 507, 1869-1885 (2021/October-3)
Estimating Teff, radius, and luminosity of M-dwarfs using high-resolution optical and NIR spectral features.
KHATA D., MONDAL S., DAS R. and BAUG T.
Abstract (from CDS):
We estimate effective temperature (Teff), stellar radius, and luminosity for a sample of 271 M-dwarf stars (M0V-M7V) observed as a part of CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) radial-velocity planet survey. For the first time, using the simultaneously observed high-resolution (R∼90 000) spectra in the optical (0.52-0.96 µm) and near-infrared (0.96-1.71 µm) bands, we derive empirical calibration relationships to estimate the fundamental parameters of these low-mass stars. We select a sample of nearby and bright M-dwarfs as our calibrators for which the physical parameters are acquired from high-precision interferometric measurements. To identify the most suitable indicators of Teff, radius, and luminosity (log L/L☉), we inspect a range of spectral features and assess them for reliable correlations. We perform multivariate linear regression and find that the combination of pseudo-equivalent widths and equivalent width ratios of the Ca II at 0.854 µm and Ca II at 0.866 µm lines in the optical and the Mg I line at 1.57 µm in the near-infrared give the best fitting linear functional relations for the stellar parameters with root mean square errors of 99K, 0.06 R☉, and 0.22 dex, respectively. We also explore and compare our results with literature values obtained using other different methods for the same sample of M dwarfs.
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
methods: data analysis - methods: observational - techniques: spectroscopic - stars: fundamental parameters - stars: low-mass - infrared: stars
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