The detailed chemical composition of the terrestrial planet host Kepler-10

TL;DR

This study analyzes the chemical composition of Kepler-10 and its stellar twins, finding evidence of refractory element depletion consistent with terrestrial planet formation, and compares these patterns to other stars to support the planetary signature hypothesis.

Contribution

It provides a high-precision differential chemical abundance analysis of Kepler-10 and its twins, linking elemental depletion patterns to terrestrial planet formation.

Findings

Kepler-10 shows refractory element depletion relative to volatiles.

The abundance pattern suggests about 13 Earth masses of terrestrial material.

Two thick disc twins do not show depletion patterns.

Abstract

Chemical abundance studies of the Sun and solar twins have demonstrated that the solar composition of refractory elements is depleted when compared to volatile elements, which could be due to the formation of terrestrial planets. In order to further examine this scenario, we conducted a line-by-line differential chemical abundance analysis of the terrestrial planet host Kepler-10 and fourteen of its stellar twins. Stellar parameters and elemental abundances of Kepler-10 and its stellar twins were obtained with very high precision using a strictly differential analysis of high quality CFHT, HET and Magellan spectra. When compared to the majority of thick disc twins, Kepler-10 shows a depletion in the refractory elements relative to the volatile elements, which could be due to the formation of terrestrial planets in the Kepler-10 system. The average abundance pattern corresponds to ~ 13 Earth masses, while the two known planets in Kepler-10 system have a combined ~ 20 Earth masses. For two of the eight thick disc twins, however, no depletion patterns are found. Although our results demonstrate that several factors (e.g., planet signature, stellar age, stellar birth location and Galactic chemical evolution) could lead to or affect abundance trends with condensation temperature, we find that the trends give further support for the planetary signature hypothesis.