From stellar to planetary composition: Galactic chemical evolution of Mg/Si mineralogical ratio

TL;DR

This study investigates how stellar elemental ratios, especially Mg/Si, influence planet formation and composition, highlighting the role of Galactic chemical evolution in these processes.

Contribution

It reveals the impact of Galactic chemical evolution on Mg/Si ratios and their correlation with planetary host types, emphasizing the importance of chemical history in planet formation.

Findings

Low-mass planet hosts have higher [Mg/Si] ratios.

Giant planet hosts show lower [Mg/Si] ratios than field stars.

Galactic chemical evolution significantly affects Mg/Si ratios.

Abstract

The main goal of this work is to study element ratios that are important for the formation of planets of different masses. We study potential correlations between the existence of planetary companions and the relative elemental abundances of their host stars. We use a large sample of FGK-type dwarf stars for which precise Mg, Si, and Fe abundances have been derived using HARPS high-resolution and high-quality data. A first analysis of the data suggests that low-mass planet host stars show higher [Mg/Si] ratios, while giant planet hosts present [Mg/Si] that is lower than field stars. However, we found that the [Mg/Si] ratio significantly depends on metallicity through Galactic chemical evolution. After removing the Galactic evolution trend only the difference in the [Mg/Si] elemental ratio between low-mass planet hosts and non-hosts was present in a significant way. These results suggests that low-mass planets are more prevalent around stars with high [Mg/Si]. Our results demonstrate the importance of Galactic chemical evolution and indicate that it may play an important role in the planetary internal structure and composition.