Elemental Abundances of Cool Stars: A Spectroscopic Framework Applied to Five Planet-Host Stars
Year: 2026
Type: preprint
Abstract: Stellar elemental abundances provide important constraints on the chemical environments from which planets form. M and late-K dwarfs are prime targets for the characterization of small exoplanets, yet their complex spectra make accurate elemental abundance measurements challenging. In this work, we present a spectral synthesis-based framework to derive detailed abundances for cool stars from high-resolution, near-infrared spectra. We apply our framework to SPIRou YJHK spectra of five planet-host stars--GJ 9827, K2-18, TOI-1201, TOI-1685, and Barnard's Star--and derive abundances of C, O, Na, Mg, Al, Si, K, Ca, Ti, Cr, Mn, and Fe for all five stars, plus Sc, V, and Ni for a subset, with typical uncertainties of $\lesssim 0.1$ dex. Our recovered metallicities and elemental abundances are broadly consistent with expected trends and previous literature analyses of these stars. We derive stellar ratios of C/O, Mg/Si, Fe/Mg, and Fe/O and find that all five systems are broadly consistent with solar ratios, with the exception of the metal-poor Barnard's Star ([M/H] $= -0.33 \pm 0.06$ dex), which is substantially iron-poor ([Fe/H] $= -0.722 \pm 0.085$ dex). Our results establish stellar chemical baselines for interior structure and atmospheric studies of these planetary systems with the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST), while highlighting the remaining model-dependent limitations of precise abundance analyses for cool stars.
Source: arXiv (Cornell University)
Institutions: McMaster University, Université de Montréal, University of Geneva
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, McMaster University, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Canada Research Chairs, Alliance de recherche numérique du Canada, Natural Sciences and Engineering Research Council of Canada, Fonds de recherche du Québec – Nature et technologies
OpenAlex ID: W7214033645