行星宿主星 TRAPPIST-1 的同位素丰度与元素丰度

元素丰度（elemental abundance）与同位素丰度（isotopic abundance）是研究行星形成（planet formation）与恒星演化（stellar evolution）的关键示踪物。本文通过近红外（near-infrared）高分辨分光（high-resolution spectroscopy）技术，首次测定了甚小质量恒星（very low-mass star）TRAPPIST-1 的碳氧比及碳氧同位素比值。

arXiv:2608.26097v1 Announce Type: new Abstract: Elemental and isotopic abundances are key tracers of planet formation, stellar evolution, and Galactic chemical evolution. Very low-mass stars are particularly interesting in this regard, because unlike more massive or evolved stars their photospheric abundances retain the star's natal composition. Cool dwarf spectra have historically been challenging to use for measurements of chemical abundances because of the blending of molecular and atomic features. However, recent advances in molecular line lists, atmospheric models, fitting techniques and IR spectrographs have enabled the successful measurement of elemental and isotopic ratios in a few dozen very low-mass stars. Here, we present near-infrared high-resolution spectroscopy of TRAPPIST-1 covering the fundamental and overtone bands of carbon monoxide and its prominent isotopologues. From the joint analysis of the $K$-band (CFHT/SPIRou) and $M$-band (Keck/NIRSPEC) spectra, we derive the first stellar C/O ratio and the first carbon and oxygen isotope ratios for this star. We obtain a metallicity of $[\mathrm{M/H}] = 0.00 \pm 0.06$, a C/O ratio of $0.60 \pm 0.02$, $^{12}\mathrm{C}/^{13}\mathrm{C} = 154{}^{+17}_{-16}$, and $^{16}\mathrm{O}/^{18}\mathrm{O} = 490{}^{+78}_{-64}$. TRAPPIST-1 has generally solar-like elemental abundances, with a $^{12}\mathrm{C}/^{13}\mathrm{C}$ ratio that is higher than the solar value and may be modestly elevated relative to some nearby