A compositional link between rocky exoplanets and their host stars

Authors :: Vardan Adibekyan
Olivier Demangeon
Christoph Mordasini
Nuno C. Santos
Barbara M. T. B. Soares
Garik Israelian
João P. Faria
Caroline Dorn
Yoichi Takeda
Mahmoudreza Oshagh
Eder Martioli
S. C. C. Barros
Emiliano Jofré
A. A. Hakobyan
Pedro Figueira
Masanobu Kunitomo
S. G. Sousa
Elisa Delgado Mena
Romina Petrucci
Bertram Bitsch
University of Zurich
Adibekyan, Vardan
Source :: Science (New York, N.Y.). 374(6565)
Publication Year :: 2021
Abstract: Stars and planets both form by accreting material from a surrounding disk. Because they grow from the same material, theory predicts that there should be a relationship between their compositions. In this study, we search for a compositional link between rocky exoplanets and their host stars. We estimate the iron-mass fraction of rocky exoplanets from their masses and radii and compare it with the compositions of their host stars, which we assume reflect the compositions of the protoplanetary disks. We find a correlation (but not a 1:1 relationship) between these two quantities, with a slope of >4, which we interpret as being attributable to planet formation processes. Super-Earths and super-Mercuries appear to be distinct populations with differing compositions, implying differences in their formation processes.<br />Authors' version of the manuscript. Published in Science