Formation of asteroid pairs by rotational fission
Formation of asteroid pairs by rotational fission
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DOI：
10.1038/nature09315
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发表时间：
2010-08
期刊：
影响因子：
64.8
通讯作者：
P. Pravec;D. Vokrouhlický;D. Polishook;D. Scheeres;A. Harris;A. Galád;Ovidiu Vaduvescu;F. Pozo Nuñez;A. Barr;P. Longa;F. Vachier;F. Colas;D. Pray;J. Pollock;D. Reichart;K. Ivarsen;J. Haislip;A. Lacluyze;P. Kušnirák;T. Henych;F. Marchis;B. Macomber;Seth Andrew Jacobson;Y. Krugly;A. V. Sergeev;A. Leroy
中科院分区：
文献类型：
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作者：
P. Pravec;D. Vokrouhlický;D. Polishook;D. Scheeres;A. Harris;A. Galád;Ovidiu Vaduvescu;F. Pozo Nuñez;A. Barr;P. Longa;F. Vachier;F. Colas;D. Pray;J. Pollock;D. Reichart;K. Ivarsen;J. Haislip;A. Lacluyze;P. Kušnirák;T. Henych;F. Marchis;B. Macomber;Seth Andrew Jacobson;Y. Krugly;A. V. Sergeev;A. Leroy
最近，科学家们发现了一对小行星，它们有着相似的日心轨道，但并不紧密相连。对它们轨道的反向积分表明，它们以较低的相对速度轻轻分离，但没有提供对其形成机制的额外见解。先前假设的旋转裂变过程可以解释他们的形成临界预测是质量比小于约0.2，当质量比接近这个上限时，较大物体的自旋周期变长。在这里，我们报告的样本的小行星对的光度观测，揭示了质量比远小于0.2的对的原色快速旋转，其临界裂变频率附近。当质量比接近0.2时，主周期变长。当系统的总能量接近于零时，这就要求小行星对从主行星的自旋中提取越来越多的能量来逃逸。我们没有发现质量比大于0.2的小行星对。超过这个极限的旋转裂变系统没有足够的能量来破坏。我们的结论是，小行星对是由一个母小行星旋转裂变成一个原双星系统，随后在其内部系统动力学破坏后不久形成的。
Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently,,. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their formation—critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs, revealing that the primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero, requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system, which subsequently disrupts under its own internal system dynamics soon after formation.