Gap opening by extremely low-mass planets in a viscous disk

Paul C. Duffell, Andrew I. MacFadyen

    Research output: Contribution to journalArticlepeer-review


    By numerically integrating the compressible Navier-Stokes equations in two dimensions, we calculate the criterion for gap formation by a very low mass (q ∼ 10-4) protoplanet on a fixed orbit in a thin viscous disk. In contrast with some previously proposed gap-opening criteria, we find that a planet can open a gap even if the Hill radius is smaller than the disk scale height. Moreover, in the low-viscosity limit, we find no minimum mass necessary to open a gap for a planet held on a fixed orbit. In particular, a Neptune-mass planet will open a gap in a minimum mass solar nebula with suitably low viscosity (α ≲ 10-4). We find that the mass threshold scales as the square root of viscosity in the low mass regime. This is because the gap width for critical planet masses in this regime is a fixed multiple of the scale height, not of the Hill radius of the planet.

    Original languageEnglish (US)
    Article number41
    JournalAstrophysical Journal
    Issue number1
    StatePublished - May 20 2013


    • hydrodynamics
    • methods: numerical
    • planetdisk interactions
    • planets and satellites: formation
    • protoplanetary disks

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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