| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1988: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The purpose of this research is to identify families of minor planets by Kozai's method of secular perturbations and to study possible origins of the families. In fact roughly 4000 numbered minor planets were classified into 8 families by using, a, the averaged semi-major axis, the mimimum values of the orbital inclination to the orbital plane of Jupiter, ^imin, and [a(1-e^2)]^<1/2> cosi which is a kind of the z-component of the angular momentum as three stable parameters. Then the brightness distribution in each family is derived and it is compared with that of non-member minor planets with similar semi-major axis region. There is no doubt that for minor planets in any family there are many dark ones whereas there are few bright minor planets. In fact nearly a half of recently discovered minor planets which are not bright enough to have been discovered in old days belong to major families. This is a strong evidence that families were created by collisions of minor planets. However, since families are bounded in phase space by mean motion and/or secular motion commensurable regions, and, therefore, it is very diffficult to compute stable quantities with sufficient accuracy by presently available theory of the secular perturbations. Therefore, we have not yet succeeded in deriving the initial conditions for the collisions. Therefore, to understand the origin of the families qualitatively it is intended to improve the theory of the secular perturbations which can be applied to any minor planet with and without mean motion and secular motion commensurability.
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