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arXiv 1709.09533astro-ph.EP
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近地小行星1991 VG的动力学演化

Dynamical evolution of near-Earth asteroid 1991 VG

C. de la Fuente Marcos, R. de la Fuente Marcos

摘要:

1991年11月6日发现的1991 VG吸引了前所未有的关注,因为它是有史以来在类地轨道上发现的第一个近地天体。当时,有些人认为它是一个新的动力学小行星类别的第一个代表,而另一些人则认为它更有可能是人为(地球或外星)起源的。四分之一个多世纪后,这个奇特的近地天体最近被发现,新的数据可能有助于证实或排除有关其起源的早期理论。在这里,我们使用最新的数据进行独立的评估,其目前的动力学状态和短期的轨道演变。广泛的N体模拟表明,它的轨道是混沌的时间尺度超过几十年。我们确认,1991年VG在1991-1992年的前一次飞越中被地球引力短暂捕获为一个小卫星;虽然它过去是一个经常性的马蹄形瞬态共轨,将来也会返回,但它不是地球的当前共轨伴星。一个现实的近地天体轨道模型预测,像1991 VG这样的天体肯定存在,而且我们一直发现其他三个近地天体-2001 GP 2、2008 UA 202和2014 WA 366-它们在动力学上与1991 VG相似。所有这些证据都证实,没有令人信服的理由相信1991 VG不是自然的。

英文摘要:

The discovery of 1991 VG on 1991 November 6 attracted an unprecedented amount of attention as it was the first near-Earth object (NEO) ever found on an Earth-like orbit. At that time, it was considered by some as the first representative of a new dynamical class of asteroids, while others argued that an artificial (terrestrial or extraterrestrial) origin was more likely. Over a quarter of a century later, this peculiar NEO has been recently recovered and the new data may help in confirming or ruling out early theories about its origin. Here, we use the latest data to perform an independent assessment of its current dynamical status and short-term orbital evolution. Extensive N-body simulations show that its orbit is chaotic on time-scales longer than a few decades. We confirm that 1991 VG was briefly captured by Earth's gravity as a minimoon during its previous fly-by in 1991-1992; although it has been a recurrent transient co-orbital of the horseshoe type in the past and it will return as such in the future, it is not a present-day co-orbital companion of the Earth. A realistic NEO orbital model predicts that objects like 1991 VG must exist and, consistently, we have found three other NEOs --2001 GP2, 2008 UA202 and 2014 WA366-- which are dynamically similar to 1991 VG. All this evidence confirms that there is no compelling reason to believe that 1991 VG is not natural.

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