A Spectroscopic Framework for Deriving Elemental Abundances of M Dwarfs

Abstract

Measuring accurate stellar abundances of planet-forming elements is critical to our understanding of exoplanet compositions and their formation processes. While these values can be reliably derived from optical spectra for FGK-type stars, the recovery of accurate abundances for M dwarfs is complicated due to persistent discrepancies between models and observed spectra, such as blended absorption features and broad molecular bands that obscure the continuum. These lingering uncertainties in M dwarf chemical compositions inhibit our ability to accurately model the interiors and atmospheres of exoplanets around M dwarfs. To address this issue, we have built a custom framework to extract elemental abundances from the spectra of cool stars via the spectral synthesis method. We showcase our methodology as well as the derived elemental abundances for a pair of cool stars. SPIRou, with its high spectral resolution and broad near-IR wavelength range, is the ideal instrument to help mitigate the difficulties present in the recovery of M dwarf elemental abundances. By combining the capabilities of SPIRou with our framework, we are well equipped to ensure the accuracy of derived elemental abundances in M dwarfs. Our results will ultimately be applied to planet-hosting M dwarfs in order to place strong constraints on the planets’ refractory and volatile abundances, both of which are important diagnostics of planetary formation histories and interior compositions.