Determination of Fundamental Properties of M-dwarfs with New Model Atmospheres and Spectra

About 70-80% of stars in our solar and galactic neighborhood are M-dwarfs. They span a range of low masses (0.08–0.6 solar mass) and low temperatures (between 2500–4000 K), facilitating molecule formation throughout their atmospheres. Standard stellar analysis methods to accurately characterize them have thus far proved challenging—in not correctly accounting for vast variations in their atmospheric structures. Here, we introduce a new self-consistent 1—D radiative-convective thermochemical equilibrium chemistry model grid for characterizing M-dwarfs, with new model atmospheres and spectra incorporating up-to-date opacities. We present our preliminary grid-model retrievals acquiring fundamental properties (Teff, log(g), M/H, and C/O) for benchmark M+G binary stars with known metallicities and M-dwarfs with interferometrically measured angular diameters, using low-resolution SpeX data (R ~ 120). We also assess the influence of stellar photospheric heterogeneity on the acquired abundances. Overall, we demonstrate the strength in leveraging broadband molecular absorption features occurring in low-resolution M-dwarf spectra achieving robust constraints for fundamental properties of exoplanet host stars.