The Missing Link: Testing Galactic Chemical Evolution Models with the First Multi-Isotopic Abundances in Solar Twin Stars

TL;DR

This study measures isotopic abundances in solar twin stars to test galactic chemical evolution models, providing insights into stellar and planetary origins and supporting future exoplanet characterization efforts.

Contribution

First isotopic abundance measurements of $^{13}$CO and C$^{18}$O in solar twins, testing and challenging existing GCE models with new stellar data.

Findings

$^{12}$C/$^{13}$C ratios match GCE predictions

$^{16}$O/$^{18}$O ratios tentatively contradict models

Provides foundational data for exoplanet and stellar evolution studies

Abstract

We present the first isotopic abundances of both $^{13}$CO and C$^{18}$O in solar twin stars and test the results against several galactic chemical evolution (GCE) models with different nucleosynthesis prescriptions. First, we compare M-band spectra from IRTF/iSHELL to synthetic spectra generated from custom solar atmosphere models using the PHOENIX atmosphere code. Next, we compare our calculated abundances to GCE models that consider isotopic yields from massive stars, asymptotic giant branch (AGB) stars and fast-rotating stars. The $^{12}$C/$^{13}$C ratios determined for this sample of solar twins are consistent with predictions from the selected GCE models; however, the $^{16}$O/$^{18}$O ratios tentatively contradict these predictions. This project constitutes the first in a stellar chemical abundance series seeking to: (1) support the James Webb Space Telescope (JWST) as it characterizes exoplanet atmospheres, interiors, and biosignatures by providing host star abundances (2) identify how unexplored stellar abundances reveal the process of galactic chemical evolution and correlate with star formation, interior, age, metallicity, and activity; and (3) provide improved stellar ages using stellar abundance measurements. By measuring elemental and isotopic abundances in a variety of stars, we not only supply refined host star parameters, but also provide the necessary foundations for complementary exoplanet characterization studies and ultimately contribute to the exploration of galactic, stellar, and planetary origins and evolution.