Formation of the Planets

摘要: On the origin of solar system, we have investigated growing process protoplanets by capture a number planetesimals, cosidering that motions planetesimals are described primarily solutions restricted three-body problem but they changed gradually effects gas friction and mutual encounters. The results summarized as follows. Once protoplanet with mass order 1025 g or 1026 has been formed result direct collisions it is able to survived within sphere its gravitational influence (the Hill sphere) in periods about 106 108 years grows Earth (10 28 g) Jupiter's core 20 g), respectively. Goldreich Ward u others shown can be instability thin dust layer primordial nebula. 1019 smaller. In next stage moving nebula will collide mutually grow. It probable part grow small massive bodies (which hereafter called protoplanets), while mean remaining main increased of, say, 1021 g. after this stage, where gravity strong enough their spheres, theme letter. Now, consider simplified initial condition density 1010 gcm3 great same particles hereafter) rotating around Sun nearly ecliptic plane. surface taken 15 gcm2• This value above from Kusaka et al_2> for nebura near orbit. Both assumed constantly circular motions. motion particle governed following Eqs. (1) problem, disturbed encounters other particles. As usually made, adopt frame (x, y) suce coincides center-of-masses these two fixed on x-axis. Using system units which distance between bodies, angular velocity sum masses all unity, write equations as3>