An approximation for the capture radius of gaseous protoplanets

Claudio Valletta*, Ravit Helled

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Determining the heavy-element accretion rate of growing giant planets is crucial for understanding their formation and bulk composition. The solid (heavy-element) accretion rate should be carefully modelled during the various stages of giant planet formation and therefore the planetary capture radius must be determined. In some simulations that model the heavy-element accretion rate, such as in N-body simulations, the presence of the gaseous envelope is either neglected or treated in an oversimplified manner. In this paper, we present an approximation for the capture radius that does not require the numerical solution of the stellar structure equations. Our approximation for the capture radius works extremely well for various planetesimal sizes and compositions. We show that the commonly assumed constant density assumption for inferring the capture radius leads to a large error in the calculated capture radius and we therefore suggest that our approximation should be implemented in future simulations.

Original languageEnglish
Pages (from-to)L62-L66
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - 1 Oct 2021
Externally publishedYes


FundersFunder number
National Centre for Competence in Research
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung200020 188460


    • Gaseous planets
    • Methods: numerical
    • Planet-disc interactions
    • Planets and satellites: formation
    • Protoplanetary discs


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