# A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e

## TL;DR

This paper proposes that the composition and density of certain Super-Earths are influenced by the temperature-dependent condensation of rocky materials in their formation zones, suggesting a new class with distinct interior properties.

## Contribution

It introduces a hypothesis linking condensation temperatures to planetary composition and identifies candidate planets as members of a new Super-Earth class with unique mineralogy and lower densities.

## Key findings

- HD 219134 b's lower density may be due to Ca, Al-rich minerals.
- Current measurement uncertainties limit definitive conclusions.
- Identifies 55 Cnc e and WASP-47 e as potential new Super-Earths with unique compositions.

## Abstract

We hypothesise that differences in the temperatures at which the rocky material condensed out of the nebula gas can lead to differences in the composition of key rocky species (e.g., Fe, Mg, Si, Ca, Al, Na) and thus planet bulk density. Such differences in the observed bulk density of planets may occur as a function of radial location and time of planet formation. In this work we show that the predicted differences are on the cusp of being detectable with current instrumentation. In fact, for HD 219134, the 10 % lower bulk density of planet b compared to planet c could be explained by enhancements in Ca, Al rich minerals. However, we also show that the 11 % uncertainties on the individual bulk densities are not sufficiently accurate to exclude the absence of a density difference as well as differences in volatile layers. Besides HD 219134 b, we demonstrate that 55 Cnc e and WASP-47 e are similar candidates of a new Super-Earth class that have no core and are rich in Ca and Al minerals which are among the first solids that condense from a cooling proto-planetary disc. Planets of this class have densities 10-20% lower than Earth-like compositions and may have very different interior dynamics, outgassing histories and magnetic fields compared to the majority of Super-Earths.