Spectral Properties of Cool Stars: Extended Abundance Analysis of Kepler Objects of Interest

TL;DR

This study provides a comprehensive spectroscopic analysis of over 1,100 stars, including many Kepler Objects of Interest, to improve stellar parameters and elemental abundances, aiding in exoplanet characterization and understanding galactic evolution.

Contribution

It extends previous homogeneous stellar analyses to nearly 2,700 stars, including detailed abundance measurements and uncertainty assessments across different S/N ratios.

Findings

No significant difference in Mg/Si ratios between super-Earth and sub-Neptune hosts.

Updated stellar parameters lead to revised radii, masses, and ages for the sample.

Methodology for uncertainty estimation as a function of S/N ratio.

Abstract

Accurate stellar parameters and precise elemental abundances are vital pieces to correctly characterize discovered planetary systems, better understand planet formation, and trace galactic chemical evolution. We have performed a uniform spectroscopic analysis for 1127 stars, yielding accurate gravity, temperature, and projected rotational velocity in addition to precise abundances for 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Most of the stars in this sample are Kepler Objects of Interest, observed by the California-Kepler Survey (CKS) and include 1,003 stars hosting 1,562 confirmed planets. This catalog extends the uniform analysis of our previous catalog, bringing the total of homogeneously analyzed stars to almost 2,700 F, G, and K dwarfs. To ensure consistency between the catalogs, we performed an analysis of our ability to recover parameters as a function of S/N ratio and present individual uncertainties as well as functions to calculate uncertainties for parameters derived from lower S/N ratio spectra. With the updated parameters, we used isochrone fitting to derived new radii, masses and ages for the stars. Finally, we look at the Mg/Si ratios of super-Earth and sub-Neptune hosts to test whether differences in initial composition might lead to differences in planet radius. We find no differences in the Mg/Si distribution as a function of planet radius.