Beyond Pebble Isolation: Diverse Pathways to Giant Planet Formation Across Stellar and Orbital Scales
Abstract
Context. Giant planet formation requires reaching crossover mass, i.e., when the mass of the gaseous envelope becomes equal to the mass of the core, within the disc's lifetime. The formation process depends critically on the orbital distance and stellar mass. Aims. We simulate planet formation via pebble accretion up to crossover mass around stellar hosts with masses of 0.1-1.5 Msun, considering a range of formation locations, with and without Type I migration. Methods. We use a modified version of MESA that couples pebble accretion, gas accretion, and disc evolution. Results. We find that cold/warm Jupiters form, whereas in-situ formation fails at short orbital separations: viscous heating raises the isolation mass enough to assemble adequate cores, but the accompanying high disc's temperature prevents cooling and suppresses gas giant formation. This supports migration-based explanations for the origin of hot Jupiters. At large orbital distances, crossover can be reached before pebble isolation mass. This is possible due to efficient envelope contraction in the cold, low-opacity outer disc. Inferred core masses at crossover range between 0.7 and 20 M_Earth. Conclusions. Pebble accretion accommodates multiple formation pathways. Giant planets can also have very small cores. Overall, different formation conditions significantly influence planetary growth and can explain the diversity in compositions and internal structures observed in the exoplanet population.
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BibTeX
@misc{peerani2026beyond,
title = {{Beyond Pebble Isolation: Diverse Pathways to Giant Planet Formation Across Stellar and Orbital Scales}},
author = {Lorenzo Peerani and Sho Shibata and Ravit Helled},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09382},
eprint = {2609.09382},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09382},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Beyond Pebble Isolation: Diverse Pathways to Giant Planet Formation Across Stellar and Orbital Scales
AU - Lorenzo Peerani
AU - Sho Shibata
AU - Ravit Helled
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.09382
UR - https://arxiv.org/abs/2609.09382
AB - Context. Giant planet formation requires reaching crossover mass, i.e., when the mass of the gaseous envelope becomes equal to the mass of the core, within the disc's lifetime. The formation process depends critically on the orbital distance and stellar mass. Aims. We simulate planet formation via pebble accretion up to crossover mass around stellar hosts with masses of 0.1-1.5 Msun, considering a range of formation locations, with and without Type I migration. Methods. We use a modified version of MESA that couples pebble accretion, gas accretion, and disc evolution. Results. We find that cold/warm Jupiters form, whereas in-situ formation fails at short orbital separations: viscous heating raises the isolation mass enough to assemble adequate cores, but the accompanying high disc's temperature prevents cooling and suppresses gas giant formation. This supports migration-based explanations for the origin of hot Jupiters. At large orbital distances, crossover can be reached before pebble isolation mass. This is possible due to efficient envelope contraction in the cold, low-opacity outer disc. Inferred core masses at crossover range between 0.7 and 20 M_Earth. Conclusions. Pebble accretion accommodates multiple formation pathways. Giant planets can also have very small cores. Overall, different formation conditions significantly influence planetary growth and can explain the diversity in compositions and internal structures observed in the exoplanet population.
ER -