[P-PS07] [JJ] 惑星科学

[PPS07-P10] 楕円軌道惑星による小天体の一時捕獲

*樋口 有理可¹、井田 茂² (1.東京工業大学、2.東京工業大学地球生命研究所)

キーワード：火星衛星、小惑星

We have investigated the probability of temporary capture of asteroids in eccentric orbits by a planet in a circular or an eccentric orbit by analytical and numerical calculations. We found that in the limit of the circular orbit, the capture probability is ~0.1% of encounters to the planet's Hill sphere, independent of planetary mass and semimajor axis. In general, the temporary capture becomes difficult, as the planet's eccentricity (e_p) increases. We found that the capture probability is almost independent of e_p until a critical value (e_p^c) that is given by ~5 times of Hill radius scaled by the planet's semimajor axis. For e_p> e_p^c, the probability decreases approximately in proportional to e_p^-1. The current orbital eccentricity of Mars is several times larger than e_p^c. However, since the range of secular change in Martian eccentricity overlaps e_p, the capture of minor bodies by the past Mars is not ruled out.