Drag on a Gravitating Sphere Moving through a Gas : Astrophysics and Relativity

概要

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The gas drag plays important roles on the process of planetary formation. Former calculations of this process used the drag coefficient of a gravity free body, but the coefficient is expected to change significantly when the effect of gravity is taken into account. The purpose of this paper is to find how the drag on a body depends on gravitational force in order to estimate a correct time scale for planetary growth. Numerical calculations of the drag on a gravitating sphere of mass M_* and radius r_0 travelling in a gascous medium with constant velocity are presented. A relation C_t = a+bΓ^2 for drag coefficient, C_t, gives close fit with the calculated values for large C_t whereΓ=GM_*/r_0 V_∞^2 . For supersonic flow, C_t depends strongly on Γ and b is as large as 10〜30. The time scale for planetary formation will probably be reduced by a factor of 2〜3.
理論物理学刊行会の論文
1985-08-25