Gomes R, Levison H F, Tsiganis K, Morbidelli A
ON/MCT and GEA/OV/UFRJ, Ladeira do Pedro Antonio, 43 Centro 20.080-090, Rio de Janeiro, RJ, Brazil.
Nature. 2005 May 26;435(7041):466-9. doi: 10.1038/nature03676.
The petrology record on the Moon suggests that a cataclysmic spike in the cratering rate occurred approximately 700 million years after the planets formed; this event is known as the Late Heavy Bombardment (LHB). Planetary formation theories cannot naturally account for an intense period of planetesimal bombardment so late in Solar System history. Several models have been proposed to explain a late impact spike, but none of them has been set within a self-consistent framework of Solar System evolution. Here we propose that the LHB was triggered by the rapid migration of the giant planets, which occurred after a long quiescent period. During this burst of migration, the planetesimal disk outside the orbits of the planets was destabilized, causing a sudden massive delivery of planetesimals to the inner Solar System. The asteroid belt was also strongly perturbed, with these objects supplying a significant fraction of the LHB impactors in accordance with recent geochemical evidence. Our model not only naturally explains the LHB, but also reproduces the observational constraints of the outer Solar System.
月球上的岩石学记录表明，在行星形成约7亿年后，撞击率出现了灾难性的激增；这一事件被称为晚期重轰炸期（LHB）。行星形成理论无法自然地解释在太阳系历史如此晚期出现的小行星剧烈撞击时期。已经提出了几种模型来解释晚期撞击激增，但没有一个是在太阳系演化的自洽框架内提出的。在这里，我们提出晚期重轰炸期是由巨行星的快速迁移引发的，这种迁移发生在长期静止期之后。在这次迁移爆发期间，行星轨道之外的小行星盘变得不稳定，导致小行星突然大量涌入内太阳系。小行星带也受到了强烈扰动，根据最近的地球化学证据，这些天体提供了晚期重轰炸期撞击体的很大一部分。我们的模型不仅自然地解释了晚期重轰炸期，还再现了外太阳系的观测约束。
