Yarkovsky-driven leakage of Koronis family members I. The case of 2953 Vysheslavia

The orbit of the asteroid 2953 Vysheslavia is currently locked in a tiny ch aotic zone very close to the 5:2 mean motion jovian resonance. Its dynamica l lifetime is estimated to be of the order of only about 10 Myr. Since Vysh eslavia is a member of the Koronis family, such a short dynamical lifetime opens a variety of interesting questions concerning its origin and evolutio n. A. Milani and P. Farinella (1995, Icarus 115, 209-212) considered a numb er of plausible scenarios and suggested that most probably Vysheslavia is a n outcome of a recent secondary fragmentation event in the family. Here we propose that Vysheslavia might have been placed on its peculiar orbit by a slow inward drift of the semimajor axis due to the Yarkovsky effect. Numeri cal simulations confirm that such evolutionary processes can take 100-500 M yr, a period comparable to but still shorter than the probable age of the f amily ton the order of a Gyr), depending on the thermal properties of Vyshe slavia's surface, the orientation of its spin axis, and its size. we have a lso integrated orbits of the asteroids 7340 (1991 UA(2)) and 1993 FR58, loc ated very close to but outside the chaotic zone that triggers Vysheslavia's orbit instability, and we show that the orbits of these asteroids may also slowly evolve toward the chaotic zone. Such an erosion of the asteroid fam ilies, caused by a slow leakage to the nearby powerful resonances, could be fairly common in the main asteroid belt. (C) 2001 Academic Press.