On the formation of super-Jupiters: Core Accretion or Gravitational Instability?

TL;DR

This study investigates whether super-Jupiters can form via Core Accretion by analyzing metallicity data of planetary systems, providing evidence that massive planets above 4 Jupiter masses can indeed form through this process.

Contribution

The paper presents observational evidence supporting the feasibility of forming super-Jupiters via Core Accretion, challenging previous assumptions that gravitational instability is necessary.

Findings

Planets over 4 Mjup form in metal-rich disks, often exceeding solar metallicity.

Massive Jupiters can form through Core Accretion given sufficient metallicity.

Metallicity in host disks correlates with planet mass, supporting Core Accretion viability.

Abstract

The Core Accretion model is widely accepted as the primary mechanism for forming planets up to a few Jupiter masses. However, the formation of super-massive planets remains a subject of debate, as their formation via the Core Accretion model requires super-solar metallicities. Assuming stellar atmospheric abundances reflect the composition of protoplanetary disks, and that disk mass scales linearly with stellar mass, we calculated the total amount of metals in planet-building materials that could contribute to the formation of massive planets. In this work, we studied a sample of 172 Jupiter-mass planets and 93 planets with masses exceeding 4 Mjup. Our results consistently demonstrate that planets with masses above 4 Mjup form in disks with at least as much metal content as those hosting planets with masses between 1 and 4 Mjup, often with slightly higher metallicity, typically exceeding that of the proto-solar disk. We interpret this as strong evidence that the formation of very massive Jupiters is feasible through Core Accretion and encourage planet formation modelers to test our observational conclusions.