Composition of super-Earths, super-Mercuries, and their host stars

Abstract

Because of their common origin, it was assumed that the composition of planet building blocks should, to a first order, correlate with stellar atmospheric composition, especially for refractory elements. In fact, information on the relative abundance of refractory and major rock-forming elements such as Fe, Mg, Si has been commonly used to improve interior estimates for terrestrial planets. Recently Adibekyan et al. (2021) presented evidence of a tight chemical link between rocky planets and their host stars. In this study we add six recently discovered exoplanets to the sample of Adibekyan et al and re-evaluate their findings in light of these new data. We confirm that i) iron-mass fraction of rocky exoplanets correlates (but not a 1:1 relationship) with the composition of their host stars, ii) on average the iron-mass fraction of planets is higher than that of the primordial iron-mass fraction of the protoplanetary disk, iii) super-Mercuries are formed in disks with high iron content. Based on these results we conclude that disk-chemistry and planet formation processes play an important role in the composition, formation, and evolution of super-Earths and super-Mercuries.

Peer-reviewed conference (Astronomy in the Crossroads of Interdisciplinary and Multidisciplinary Sciences) proceeding

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Cited by in corpus (5)

• Nucleation and growth of iron pebbles explains the formation of iron-rich planets akin to Mercury
• The HD 93963 A transiting system: A 1.04d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS
• Linking the primordial composition of planet building disks to the present-day composition of rocky exoplanets
• A Reanalysis of the Composition of K2-106b: an Ultra-short Period Super-Mercury Candidate
• A chemical perspective on planet formation in reduced systems