Abundances of Elements in Solar Systems

TL;DR

This paper discusses how stellar and planetary compositions are linked, using white dwarf observations to infer exoplanet interior compositions and comparing them to Solar System meteorites.

Contribution

It introduces a method of using white dwarf pollution data to analyze exoplanet compositions and compares these to Solar System meteorites, providing new insights into planetary formation.

Findings

Extrasolar rock compositions are similar to Solar System chondritic meteorites.

White dwarf pollution observations can reveal exoplanet interior compositions.

Stellar elemental abundances help distinguish planetary formation histories.

Abstract

The relationship between stars and planets provides important information for understanding the interior composition, mineralogy, and overall classification of small planets (R $\lesssim$ 3.5R$_{\oplus}$). Since stars and planets are formed at the same time and from the same material, their compositions are inextricably linked to one another, especially with respect refractory elements like Mg, Si, and Fe. As a result, stellar elemental abundances can help break the degeneracy inherent to planetary mass-radius models and determine whether planets may be similar to the Earth in composition or if additional factors, such as formation near the host star or a giant impact, may have influenced the planet's make-up. To this end, we now have observations of the abundances of extrasolar rocks that were pulled onto the surfaces of a white dwarfs, whose compositions act as a direct insight into the interiors of small exoplanets. From measurements of $\sim$30 of these "polluted" white dwarfs, we have found that composition of the extrasolar rocks are similar to Solar System chondritic meteorites.