Stellar Parameter Estimation for Half a Million LAMOST M Dwarfs based on Cycle-StarNet

As the most common and numerous stellar members of the Milky Way galaxy and key candidates for hosting terrestrial planets, M dwarfs are of significant importance in various astronomical studies. This work provides basic atmospheric parameters (Teff , log g, [M/H]), and radial velocity (RV) for over 500,000 M dwarfs in LAMOST DR10. Utilizing the domain-adaptation approach Cycle-StarNet, we bridged the gap between LAMOST low-resolution observed spectra and PHOENIX synthetic spectra. The information from the PARSEC stellar evolution model constrained the parameter space of the synthetic domain, reducing errors due to parameter degeneracy. The accuracy derived from comparison to available APOGEE DR17 and Gaia DR3 results of Teff , log g, [M/H], and RV are −2±54 K, 0.12±0.07 dex, 0.05±0.14 dex, and 3±9 km s−1, respectively. The precision of these parameters measured from multiple observed objects is 61 K, 0.07 dex, 0.15 dex, and 12 km s−1, respectively. With the increase in the spectral quality, both the accuracy and precision further improve. The complete catalog is made electronically accessible.