Planetary growth with collisional fragmentation and gas drag

Hiroshi Kobayashi*, Hidekazu Tanaka, Alexander V. Krivov, Satoshi Inaba


研究成果: Article査読

81 被引用数 (Scopus)


As planetary embryos grow, gravitational stirring of planetesimals by embryos strongly enhances random velocities of planetesimals and makes collisions between planetesimals destructive. The resulting fragments are ground down by successive collisions. Eventually the smallest fragments are removed by the inward drift due to gas drag. Therefore, the collisional disruption depletes the planetesimal disk and inhibits embryo growth. We provide analytical formulae for the final masses of planetary embryos, taking into account planetesimal depletion due to collisional disruption. Furthermore, we perform the statistical simulations for embryo growth (which excellently reproduce results of direct N-body simulations if disruption is neglected). These analytical formulae are consistent with the outcome of our statistical simulations. Our results indicate that the final embryo mass at several AU in the minimum-mass solar nebula can reach about ∼0.1 Earth mass within 107years. This brings another difficulty in formation of gas giant planets, which requires cores with ∼10 Earth masses for gas accretion. However, if the nebular disk is 10 times more massive than the minimum-mass solar nebula and the initial planetesimal size is larger than 100km, as suggested by some models of planetesimal formation, the final embryo mass reaches about 10 Earth masses at 3-4AU. The enhancement of embryos' collisional cross sections by their atmosphere could further increase their final mass to form gas giant planets at 5-10AU in the Solar System.

出版ステータスPublished - 2010 10月

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学


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