主带中部的V型小行星
V-type asteroids in the middle Main Belt
摘要：
最近在中间带发现的第一颗V型小行星，（21238）1995 WV 7，位于2.54天文单位，提出了它是否来自（4）灶神星的问题。在本文中，我们提供的光谱观测表明存在另一个V型小行星在~2.53 AU，（40521）1999 RL 95，我们调查的可能性，这两个小行星从灶神星家族演变到它们现在的轨道上的半长轴漂移由于Yarkovsky效应。这种情况的主要问题是小行星需要与木星的3/1平均运动共振，这是非常不稳定的。结合轨道演化的数值模拟，其中包括Yarkovsky效应，与蒙特卡洛模型，我们计算的概率给定直径D的小行星从灶神星家庭和跨越3/1共振，达到稳定的轨道在中间带。我们的研究结果表明，像（21238）1995 WV 7这样的小行星由于其大尺寸（约5公里），通过这种机制进化的可能性很低。然而，如果我们假设灶神星家族形成于3.5戈瑞之前，这个机制或许可以解释像（40521）1999 RL 95（~3公里）这样的较小天体的轨道。我们估计约有10%或更多的D>1 km的V型天体可能通过跨越3/1共振而来自灶神星族。剩下的90%应该是另一个来源。
英文摘要：
The recent discovery of the first V-type asteroid in the middle belt, (21238) 1995WV7, located at ~2.54 AU, raises the question of whether it came from (4) Vesta or not. In this paper, we present spectroscopic observations indicating the existence of another V-type asteroid at ~2.53 AU, (40521) 1999RL95, and we investigate the possibility that these two asteroids evolved from the Vesta family to their present orbits by drifting in semi-major axis due to the Yarkovsky effect. The main problem with this scenario is that the asteroids need to cross the 3/1 mean motion resonance with Jupiter, which is highly unstable. Combining numerical simulations of the orbital evolution, that include the Yarkovsky effect, with Monte Carlo models, we compute the probability of an asteroid of given diameter D to evolve from the Vesta family and to cross over the 3/1 resonance, reaching a stable orbit in the middle belt. Our results indicate that an asteroid like (21238) 1995WV7 has a low probability of having evolved through this mechanism due to its large size (~5 km). However, the mechanism might explain the orbit of smaller bodies like (40521) 1999RL95 (~3 km), provided that we assume that the Vesta family formed > 3.5 Gy ago. We estimate that about 10% or more of the V-type bodies with D>1 km may come from the Vesta family by crossing over the 3/1 resonance. The remaining 90% must have a different origin.
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