Reconciliation of M Dwarf and FGK Stellar Abundances with Galactic Chemical Evolution

Previous studies report apparent chemical abundance discrepancies between M dwarfs and FGK stars in the solar neighborhood, raising questions about the origin of these differences. Using a statistical pipeline, we revisit whether M dwarf abundance ratios are consistent with non–local thermodynamic equilibrium (non-LTE) measurements of FGK stars, and independently validate these results with predictions from state-of-the-art Galactic chemical evolution (GCE) models of the Milky Way’s thin disk. Abundance trends for [C, O, Na, Mg, Al, Si, Ca, Ti, Ni/H] versus [Fe/H] are derived for a benchmark sample of 47 M dwarfs from the APOGEE, CARMENES, and Subaru/InfraRed Doppler (IRD) surveys. These are compared to non-LTE measurements of FGK stars and to GCE predictions calculated with the open-source code OMEGA+ . Our predictions take into account the intrinsic metallicity scatter of the solar neighbourhood and different stellar yield sets. We find that the M dwarf trends align with FGK stars within uncertainties for most elements (C, O, Na, Al, Si, Ni), resolving prior discrepancies. The observational trends also agree well with GCE predictions. However, the Ti trends are not consistent between spectroscopic samples, likely due to systematic differences in abundance determination techniques. We also show that M dwarf abundances differ significantly between different surveys in the literature. The abundance ratios of M dwarfs and FGK stars are mostly chemically consistent in the solar neighborhood and can be effectively modeled. GCE slopes provide an independent benchmark of these compositional trends.