Elemental Abundances of Kepler Objects of Interest in APOGEE DR17

TL;DR

This study compares elemental abundances of Kepler planet host stars with a matched reference sample, finding no significant differences, and establishes the abundance precision needed to detect potential planet formation signatures.

Contribution

It introduces a method to compare elemental abundances of planet hosts with matched stars, setting an upper limit on the precision needed to identify chemical signatures of planet formation.

Findings

No significant abundance differences between planet hosts and reference stars.

Median intrinsic dispersion of ~0.038 dex for KOIs.

Establishes abundance precision threshold for detecting planet formation signatures.

Abstract

The elemental abundances of planet host stars can shed light on the conditions of planet forming environments. We test if individual abundances of 130 known/candidate planet hosts in APOGEE are statistically different from those of a reference doppelganger sample. The reference set comprises objects selected with the same Teff, logg, [Fe/H], and [Mg/H] as each Kepler Object of Interest (KOI). We predict twelve individual abundances (X = C, N, O, Na, Al, Si, Ca, Ti, V, Cr, Mn, Ni) for the KOIs and their doppelgangers using a local linear model of these four parameters, training on ASPCAP abundance measurements for a sample of field stars with high fidelity (SNR > 200) APOGEE observations. We compare element prediction residuals (model-measurement) for the two samples and find them to be indistinguishable, given a high quality sample selection. We report median intrinsic dispersions of ~0.038 dex and ~0.041 dex, for the KOI and doppelganger samples, respectively, for these elements. We conclude that the individual abundances at fixed Teff, logg, [Fe/H], and [Mg/H] are unremarkable for known planet hosts. Our results establish an upper limit on the abundance precision required to uncover any chemical signatures of planet formation in planet host stars.