![Plots of the observed, high signal-to-noise H (top panel) band IGRINS spectra used in this abundance analysis. Oxygen abundances are determined from OH lines located in the H band (1.45–1.80 microns) while carbon, 12C/ 13C, and 16O/ 18O abundances are derived from various CO isotopologue lines located in the 2.3-2.45 micron region of the K band (1.95–2.45 microns). -- [astro-ph.SR]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/11/Expanding.png?fit=1200%2C679&ssl=1)
[astro-ph.SR] There are exceedingly few chemical abundance measurements available in the literature for K dwarf stars, especially for those with Teff< 4700 K due to an incompatibility of traditional analyses with their molecular-line-ridden optical spectra.
To address the need for K dwarf abundance constraints, we present an elemental ([C/H], [O/H]) and isotopic (12C/13C, 16O/18O) abundance analysis for six K dwarf exoplanet host stars: K2-141, NGTS-10, WASP-43, WASP-69, WASP-80, and HATS-72.
Each system hosts an exoplanet targeted by JWST characterization efforts, making host star abundances especially critical as baseline references. Using MARCS model atmospheres, the TurboSpectrum spectral synthesis code, and near-infrared IGRINS spectra, we derive novel [C/H] and [O/H] abundance ratios for these high-priority K dwarf host stars. We further investigate prospects for determining 12C/13C and 16O/18O ratios using 13C16O and 12C18O lines from the 2.3 micron CO bandhead.
The observed spectra are too noisy to measure 16O/18O ratios for the sample, but we do find sub-solar 12C/13C ratios for five out of six targets. We also derive uniform gyrochronological ages for each host star to compare with galactic chemical evolution models and identify underlying abundance-age trends. NIR H+K band spectroscopy provides an alternative to optical, atomic line-derived carbon and oxygen abundances for cool dwarf stars.
The growing catalog of precise host star elemental and isotopic abundances complements ongoing observations of their companions and provides a baseline for understanding their chemical composition, origin, and evolution.
David R. Coria, Neda Hejazi, Ian J. M. Crossfield, Ismael Mireles, Casey L. Brinkman, Jared R. Kolecki, Emilio Marfil, Thomas Nordlander, Lauren M. Weiss, Diana Dragomir
Comments: 32 pages, 6 figures, 5 tables. Accepted for publication in ApJ (11/3/2026)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2611.08676 [astro-ph.SR] (or arXiv:2611.08676v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2611.08676
Focus to learn more
Submission history
From: David Coria
[v1] Thu, 5 Nov 2026 20:34:01 UTC (3,197 KB)
https://arxiv.org/abs/2611.08676
Astrobiology,
