一颗长周期彗星的分裂是恐龙灭绝的起源
Breakup of a Long-Period Comet as the Origin of the Dinosaur Extinction
摘要：
希克苏鲁伯撞击物的起源，被认为是K/T大灭绝事件的原因，是一个未解之谜。主带小行星和长周期彗星的背景撞击率以前被认为太低，无法解释希克苏鲁伯撞击事件。在这里，我们展示了一小部分长周期彗星在靠近太阳后被潮汐破坏，每个彗星都产生了一系列穿过地球轨道的较小碎片。这些彗星群可能会使能够产生希克苏鲁伯撞击事件的长周期彗星的撞击率增加一个数量级。这一新的速率与希克苏鲁伯撞击坑的年龄相一致，从而为撞击物的起源提供了令人满意的解释。我们的假设解释了地球历史上最大的确认撞击坑的组成，以及过去百万年中最大的撞击坑。它预测，与主带小行星的陨石坠落所预期的相比，具有碳质碎屑成分的撞击物所占的比例更大。
英文摘要：
The origin of the Chicxulub impactor, which is attributed as the cause of the K/T mass extinction event, is an unsolved puzzle. The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Here, we show that a fraction of long-period comets are tidally disrupted after passing close to the Sun, each producing a collection of smaller fragments that cross the orbit of Earth. This population could increase the impact rate of long-period comets capable of producing Chicxulub impact events by an order of magnitude. This new rate would be consistent with the age of the Chicxulub impact crater, thereby providing a satisfactory explanation for the origin of the impactor. Our hypothesis explains the composition of the largest confirmed impact crater in Earth's history as well as the largest one within the last million years. It predicts a larger proportion of impactors with carbonaceous chondritic compositions than would be expected from meteorite falls of main-belt asteroids.
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