Chapter 7 Stability of the Primordial Solar Nebula : Part II Formation Processes of Protostars : Origin of the Solar System

概要

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The linear stability of the solar nebula model is examined under a two-dimensional approximation. First we investigate the general dependence of the shear instability on the rotation law in the differentially rotating isentropic cylinders. We study a cylinder in which the angular velocity has the form, Ω∝γ^<-q>, where γ is the distance from a central star. We find that the cylinder with q>1 has nonaxisymmetric unstable modes, as far as the other parameters such as the width of the cylinder and the magnitude of the sound velocity are tuned properly. Next we consider the case where the density and the sound velocity have the same radial dependence as Hayashi's solar nebula model (1981). We do only computations for the cases where the inner boundary radius is 0.4AU, the outer boundary radius is less than 2.5AU and the sound velocity is about 10 times as large as that of Hayashi's model, in order to save computational time. For the representative case where inner and outer boundaries are at 0.4AU and 1.05AU, respectively, the sound velocity at the Earth region is 0.407 times the Keplerian velocity and the azimuthal wave number m=5, the e-folding growth time is 5.4 yr. In the realistic solar nebula model, the growth time is estimated to be probably greater than the order of 10^3 yr.
理論物理学刊行会の論文
1989-03-10