Abstract
ABSTRACT Planets and stars ultimately form out of the collapse of the same cloud of gas. Whilst planets, and planetary bodies, readily loose volatiles, a common hypothesis is that they retain the same refractory composition as their host star. This is true within the Solar system. The refractory composition of chondritic meteorites, Earth, and other rocky planetary bodies are consistent with solar, within the observational errors. This work aims to investigate whether this hypothesis holds for exoplanetary systems. If true, the internal structure of observed rocky exoplanets can be better constrained using their host star abundances. In this paper, we analyse the abundances of the K-dwarf, G200-40, and compare them to its polluted white dwarf companion, WD 1425+540. The white dwarf has accreted planetary material, most probably a Kuiper belt-like object, from an outer planetary system surviving the star’s evolution to the white dwarf phase. Given that binary pairs are chemically homogeneous, we use the binary companion, G200-40, as a proxy for the composition of the progenitor to WD 1425+540. We show that the elemental abundances of the companion star and the planetary material accreted by WD 1425+540 are consistent with the hypothesis that planet and host-stars have the same true abundances, taking into account the observational errors.
Highlights
The processes occuring during planet formation have been key to our own planet’s history, structure and its development of life, just as they have been key in determining the nature of planets around other stars
Our analysis finds that the hypothesis that G200-40 and its companion WD 1425+540 share the same true abundances is more likely than the hypothesis that WD 1425+540 shares the true abundances of a random star analysed in a similar manner in this work, 61 Cyg B
Analysis of polluted white dwarfs provide the bulk composition of the exoplanetary material that they have accreted
Summary
The processes occuring during planet formation have been key to our own planet’s history, structure and its development of life, just as they have been key in determining the nature of planets around other stars. We lack a full understanding of how planet formation determines the composition of a planet. Whilst planets clearly form out of the same material as their host stars, a range of processes may occur during planet formation and evolution that alter compositions. Are less readily incorporated, into planetary bodies at high temperatures. Not all planetary bodies have experienced high temperatures. Many comets in the Solar System retain
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