[Previous] | [Session 5] | [Next]
S.I. Ipatov (George Mason Univ., USA; Inst. Applied Math., Moscow), J.C. Mather (LASP, NASA/GSFC), J.U. Guillory (George Mason Univ.)
We studied the orbital evolution of dust particles under the gravitational influence of planets (excluding Pluto), radiation pressure, Poynting--Robertson drag, and solar wind drag. Initial positions and velocities of considered asteroidal and kuiperoidal particles were the same as those of the discovered main-belt asteroids and trans-Neptunian objects, respectively. We considered cometary particles started from Comet 2P Encke. The values of the ratio \beta between the radiation pressure force and the gravitational force varied from 0.0004 to 0.4 (for silicates, such values correspond to particle diameters d between 1000 and 1 microns; for water ice, the diameters are greater by a factor of 3 than those for silicates). The mean probabilities P of collisions of asteroidal and cometary dust particles with Earth and Venus during lifetimes of particles were maximum at \beta~0.002-0.004 (i.e., at d~100-200 microns for silicate particles). At \beta\ge0.01 the values of P and the mean times T spent by particles in Earth-crossing and Venus-crossing orbits quickly decrease with an increase of \beta (usually P\propto1/\beta and T\propto1/\beta). At \beta~0.0004-0.001 the values of P and T for asteroidal dust particles were smaller than those at \beta~0.002-0.004, though maximum times until collisions of particles with the Sun were greater for smaller \beta (greater times were needed for larger particles to migrate to the orbits of the terrestrial planets). Cratering records showed that the peak of diameters of dust particles colliding with the Earth was at 200 microns. This is in accordance with our simulations, if the number of particles with diameters greater than D is proportional to D-\alpha, where \alpha~2-3. At \beta\ge0.02 and \beta\le0.001 some asteroidal particles (\le4 % at \beta\le0.1) migrated beyond Jupiter's orbit. A few asteroidal particles collided with the Sun after moving outside Jupiter's orbit for a long time. 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. At \beta~0.05-0.4 the probability of collisions of kuiperoidal dust particles with the Sun was 0.1-0.2. Preliminary results can be found in http://arXiv.org/format/astro-ph/0308450. This work was supported by NASA (NAG5-10776) and INTAS (00-240).
[Previous] | [Session 5] | [Next]
Bulletin of the American Astronomical Society, 36 #2
© 2004. The American Astronomical Soceity.