Metallicity regulates planet formation across all masses

TL;DR

This study demonstrates that stellar metallicity significantly influences planet formation across all masses, with more massive planets forming preferentially in metal-rich environments, supporting core accretion theory.

Contribution

It provides empirical evidence linking metallicity to the entire spectrum of planetary masses, emphasizing its central role in planet formation.

Findings

Massive planets are more common in metal-rich environments.

Planetary system multiplicity correlates with metallicity.

Only the upper planetary mass range shows a strong positive correlation with metallicity.

Abstract

The role of stellar metallicity in shaping planetary systems is central to our understanding of planet formation. While the core accretion paradigm is widely accepted as the dominant mechanism for forming low- and intermediate-mass planets, the origin of the most massive planets remains debated, with gravitational instability often invoked to explain their existence. In this study, we analyze the dependence of planet formation on metallicity using the total heavy-element mass fraction (Z), which is a proxy for the composition of the protoplanetary disk inferred from stellar photospheres. We show that even the most massive planets form preferentially in metal-rich environments. Z correlates not only with the presence of planets, but also with planetary system multiplicity and total planetary mass. The most massive planets are found in the most metal-rich environments, and, in agreement with core-accretion theory, only the upper end of the planetary mass distribution shows a clear positive correlation with metallicity. These findings suggest that the chemical enrichment of protoplanetary disks plays a central role in shaping the full spectrum of planetary masses.