Stellar Parameters of BOSS M Dwarfs in SDSS-V DR19

Abstract We utilize the Stellar LAbel Machine (SLAM), a data-driven model based on support vector regression, to derive the stellar parameters (Fe/H, T eff , and log g ) for Sloan Digital Sky Survey V M dwarfs using low-resolution optical spectra ( R ∼ 2000) obtained with the BOSS spectrographs. These parameters are calibrated using LAMOST F, G, or K dwarf companions (Fe/H) and APOGEE Net ( T eff and log g ), respectively. Comparisons of the SLAM-predicted Fe/H values between the two components of M+M dwarf wide binaries show no bias but a scatter of 0.11 dex. Further comparisons with two other works, which also calibrated the Fe/H of M dwarfs by using the F/G/K companions, reveal biases of −0.06 ± 0.16 dex and 0.02 ± 0.14 dex, respectively. The SLAM-derived effective temperatures agree well with temperatures that are calibrated by using interferometric angular diameters (bias −27 ± 92 K) and those of LAMOST (bias −34 ± 65 K) but are systematically lower than those from an empirical relationship between the color index and T eff by 146 ± 45 K. The SLAM surface gravity aligns well with those of LAMOST (bias −0.01 ± 0.07 dex) and those derived from the stellar mass and radius (bias −0.04 ± 0.09 dex). Finally, we investigate a bias in Fe/H between SLAM and APOGEE ASPCAP. This depends on ASPCAP’s Fe/H and T eff , and we provide an equation to correct the ASPCAP metallicities.