Planetary Sciences American and Soviet Research/Proceedings from the U.S.-U.S.S.R. Workshop on Planetary Sciences (1991) / Chapter Skim
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9. The Rate of Planet Formation and the Solar System's Small Bodies
9. The Rate of Planet Formation and the Solar System's Small Bodies
Pages 116-125
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From page 116... ...
bodies of the Jovian zone penetrate the asteroid zone too late and do not have time to hinder the formation of a normal-sized planet in the astroidal zone and thereby remove a significant portion of the mass of solid matter and (b) Uranus and Neptune cannot eject bodies from the solar system into the cometary cloud.
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From page 117... ...
117 _, (1) where m and r are the mass and radius of the Secreting planet, P is its period of revolution around the Sun, p and ~ are the volume and surface density of solid matter in a planet's zone, and ~ is the dimensionless parameter characterizing random velocities of bodies in a planet's zone (in relation to the Kepler circular velocity of a preplanetary swarm's rotation)
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From page 118... ...
At the same time, we conducted a qualitative study of the coagulation equation for preplanetary bodies. This effort yielded asymptotic solutions in the form of an inverse power law with an exponent q: n(~m)
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From page 119... ...
Since they are not only removed from the solar system, but also to its outer region primarily, a source of bodies was thereby discovered which formed the cometary cloud. The basic possibility of runaway growth, that is "runaway" in terms of the mass of the largest body from the general distribution of the mass of the remaining bodies in its feeding zone, has been demonstrated (Safronov 1969~.
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From page 120... ...
If the bunk of the mass in this distribution had been concentrated in the larger bodies, for example, if it had been compatible with the power law (4) with the exponent q < 2, the relative velocities of bodies could have been written in the form (2)
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From page 121... ...
Lissauer estimates the growth rate of m using the usual formula (1~. Assuming random velocities of bodies until their encounters with a protoplanet to be extremely low, he assumes that after the encounter they approximate the difference of Kepler circular velocities at a distance of AR = rH.
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From page 123... ...
Subsequent estimates have shown that the JZB could only have removed about one half of the initial mass of AZ matter (Safronov 1979~. In 1973, Cameron and Pine proposed a resonance mechanism by which resonances scan the AZ during the dissipation of gas from solar nebulae.
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From page 124... ...
of a gaseous solar nebula of n = 3/2 yields dra ~ drj, that is, it does not cause asteroid growth to lag behind JZB. In order for JZB's to have effectively swept bodies out of the AZ, there would have to have been a slower drop of crg(R)
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From page 125... ...
1978. Maximum masses, distances and accumulation time scales for terrestrial planets.
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