  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.

Earth and Planetary Astrophysics;Solar and Stellar Astrophysics