"Migration of small bodies and dust in the solar system"
Sergei Ipatov (Catholic University of America)
Abstract:
Computer simulations of the orbital evolution of Jupiter-family comets (JFCs), resonant asteroids, and asteroidal, trans-Neptunian, and cometary dust particles were made. The gravitational influence of planets was taken into account. For dust particles we also considered radiation pressure, Poynting-Robertson drag, and solar wind drag. A few JFCs got Earth-crossing orbits with semi-major axes a<2 AU and aphelion distance Q<4.2 AU and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myrs), some of these former JFCs even got inner-Earth orbits (with Q<0.983 AU) or Aten orbits for Myrs. The probability of a collision of one of such objects, which move for millions of years inside Jupiter's orbit, with a terrestrial planet can be greater than analogous total probability for thousands other objects. If those former JFCs that got near-Earth object (NEO) orbits for millions of years didn't disintegrate during this time, there could be many extinct comets among NEOs. The obtained results show that during the accumulation of the giant planets the total mass of icy bodies delivered to the Earth could be about the mass of water in Earth's oceans. In our runs for dust particles, the values of the ratio β between the radiation pressure force and the gravitational force varied from 0.0004 to 0.4 (for silicates, such values of β correspond to particle diameters between 1000 and 1 microns). The maximum probability of a collision of an asteroidal or cometary dust particle with the Earth during its lifetime was for diameter d~100 microns. At d<10 micron, the collision probability of a trans-Neptunian particle with the Earth during a lifetime of the particle was less than that for an asteroidal particle by only a factor of several. The peaks in the distribution of migrating asteroidal dust particles with semi-major axis corresponding to the n:(n+1) resonances with Earth and Venus and the gaps associated with the 1:1 resonances with these planets are more pronounced for larger particles. We investigated how the solar spectrum is changed by scattering by dust particles and compared computer simulation results with observations. Several our papers on this problem were put in
http://arXiv.org/format/astro-ph/ (e.g., 0305519, 0308448, 0308450, 0411004).