Dead zones and extrasolar planetary properties

Soko Matsumura, Ralph E. Pudritz

    Research output: Contribution to journalArticle

    40 Citations (Scopus)

    Abstract

    Most low-mass protostellar discs evolve in clustered environments where they are affected by external radiation fields, while others evolve in more isolated star-forming regions. Assuming that the magnetorotational instability (MRI) is the main source of viscosity, we calculate the size of a poorly ionized, MRI inactive and hence low viscosity region - the 'dead zone' -in these protostellar discs. We include disc ionization by X-rays, cosmic rays, radioactive elements and thermal collisions, recombination by molecules, metals and grains, as well as the effect of turbulence stimulation in the dead zone by the active layers lying above it. We also calculate the gap-opening masses of planets, which are determined by a disc's viscosity and a disc aspect ratio, for discs in these environments and compare them with each other. We find that the dead zone is a robust feature of the protostellar discs that is largely independent of their environment, typically stretching out to ~15 au. We analyse the possible effects of dead zones on planet formation, migration and eccentricity evolution. We show that the gap-opening mass inside the dead zone is expected to be of the order of terrestrial and ice giant mass planets while that outside the dead zone is Jovian or super-Jovian mass planets, largely independent of the star-forming environment. We show that dead zones can significantly slow down both type I and type 11 planetary migration due to their lower viscosity. We also find that the growth of eccentricity of massive extrasolar planets is particularly favourable through the planet - disc interaction inside the dead zones due to the large gaps expected to be opened by planets.
    Original languageEnglish
    Pages (from-to)572-584
    Number of pages13
    JournalMonthly Notices of the Royal Astronomical Society
    Volume365
    Issue number2
    DOIs
    Publication statusPublished - 11 Jan 2006

    Fingerprint

    planet
    planets
    viscosity
    eccentricity
    stars
    active layer
    extrasolar planets
    stimulation
    radioactive isotopes
    radiation distribution
    cosmic ray
    recombination
    aspect ratio
    cosmic rays
    ice
    ionization
    collision
    turbulence
    collisions
    metal

    Keywords

    • accretion
    • accretion disks
    • TURBULENCE
    • planets and satellites: general
    • solar system: formation
    • planetary systems : formation
    • planetary system: protoplanetary disks

    Cite this

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    abstract = "Most low-mass protostellar discs evolve in clustered environments where they are affected by external radiation fields, while others evolve in more isolated star-forming regions. Assuming that the magnetorotational instability (MRI) is the main source of viscosity, we calculate the size of a poorly ionized, MRI inactive and hence low viscosity region - the 'dead zone' -in these protostellar discs. We include disc ionization by X-rays, cosmic rays, radioactive elements and thermal collisions, recombination by molecules, metals and grains, as well as the effect of turbulence stimulation in the dead zone by the active layers lying above it. We also calculate the gap-opening masses of planets, which are determined by a disc's viscosity and a disc aspect ratio, for discs in these environments and compare them with each other. We find that the dead zone is a robust feature of the protostellar discs that is largely independent of their environment, typically stretching out to ~15 au. We analyse the possible effects of dead zones on planet formation, migration and eccentricity evolution. We show that the gap-opening mass inside the dead zone is expected to be of the order of terrestrial and ice giant mass planets while that outside the dead zone is Jovian or super-Jovian mass planets, largely independent of the star-forming environment. We show that dead zones can significantly slow down both type I and type 11 planetary migration due to their lower viscosity. We also find that the growth of eccentricity of massive extrasolar planets is particularly favourable through the planet - disc interaction inside the dead zones due to the large gaps expected to be opened by planets.",
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    Dead zones and extrasolar planetary properties. / Matsumura, Soko; Pudritz, Ralph E.

    In: Monthly Notices of the Royal Astronomical Society, Vol. 365, No. 2, 11.01.2006, p. 572-584.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Dead zones and extrasolar planetary properties

    AU - Matsumura, Soko

    AU - Pudritz, Ralph E.

    PY - 2006/1/11

    Y1 - 2006/1/11

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    KW - accretion disks

    KW - TURBULENCE

    KW - planets and satellites: general

    KW - solar system: formation

    KW - planetary systems : formation

    KW - planetary system: protoplanetary disks

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    EP - 584

    JO - Monthly Notices of the Royal Astronomical Society

    JF - Monthly Notices of the Royal Astronomical Society

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