Abundances of Elements in Solar Systems

The relationship between stars and planets provides important information for understanding the interior composition, mineralogy, and overall classification of small planets (R ≲ 3.5R_⊕). 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 ∼30 of these "polluted" white dwarfs, we have found that composition of the extrasolar rocks are similar to Solar System chondritic meteorites.