The Mass-Activity relationships in M and K dwarfs. I. Stellar parameters of our sample of M and K dwarfs

Eric R. Houdebine, D. J. Mullan, J. G. Doyle, Geoffroy de La Vieuville, C. J. Butler, F. Paletou

Published 2019-05-20Version 1

Empirical correlations between stellar parameters such as rotation or radius and magnetic activity diagnostics require estimates of the effective temperatures and the stellar radii. The aim of this study is to propose simple methods that can be applied to large samples of stars in order to derive estimates of the stellar parameters. Good empirical correlations between Red/Infra-Red colours (e.g. (R-I)$_C$) and effective temperatures have been well established for a long time (e.g. Veeder 1974, Bessell 1979, Leggett 1992). The more recent (R-I)$_C$ colour-$T_{eff}$ correlation using the data of Mann et al. (2015: hereafter M15) and Boyajian et al. (2012: hereafter B12) shows that this colour can be applied as a temperature estimate for large samples of stars. We find that the mean scatter in $T_{eff}$ relative to the (R-I)$_C$-$T_{eff}$ relationship of B12 and M15 data is only $\pm 3\sigma =$44.6~K for K dwarfs and $\pm 3\sigma =$39.4~K for M dwarfs. These figures are small and show that the (R-I)$_C$ colour can be used as a first guess effective temperature estimator for K and M dwarfs. We derive effective temperatures for about 1910 K and M dwarfs using the calibration of (R-I)$_C$ colour-$T_{eff}$ from B12 and M15 data. We also compiled $T_{eff}$ and metallicity measurements available in the literature using the VizieR database. We determine $T_{eff}$ for 441 stars with previously unknown effective temperatures. We also identified 21 new spectroscopic binaries and 1 triple system from our high resolution spectra.