复仇女神重新考虑
Nemesis Reconsidered
摘要：
一个伴星（涅墨西斯）围绕太阳运行的假设是由地球灭绝周期性的主张激发的，被认为是由彗星阵雨介导的。太阳的遥远伴星的轨道预计会受到银河潮汐场的扰动，并与经过的恒星相遇，这将导致周期的变化。我们研究了以前提出的周期性的证据，使用两个现代的，大大改善了古生物化石生物多样性的数据集。我们发现，有一个狭窄的峰值在27 My在这些独立的数据集之间的消光强度时间序列的交叉谱。这种周期性在一个时间段内延伸，几乎是最初注意到的两倍。在99%的置信度下，过多的灭绝事件与这种周期性有关。在这个意义上，我们确认了灭绝时间序列中最初注意到的特征。然而，我们发现，它显示非常有规律的时间约0.5 Gy。与早期的轨道摄动计算相比，时间的规律性似乎排除了复仇女神假说作为因果因素。
英文摘要：
The hypothesis of a companion object (Nemesis) orbiting the Sun was motivated by the claim of a terrestrial extinction periodicity, thought to be mediated by comet showers. The orbit of a distant companion to the Sun is expected to be perturbed by the Galactic tidal field and encounters with passing stars, which will induce variation in the period. We examine the evidence for the previously proposed periodicity, using two modern, greatly improved paleontological datasets of fossil biodiversity. We find that there is a narrow peak at 27 My in the cross-spectrum of extinction intensity time series between these independent datasets. This periodicity extends over a time period nearly twice that for which it was originally noted. An excess of extinction events are associated with this periodicity at 99% confidence. In this sense we confirm the originally noted feature in the time series for extinction. However, we find that it displays extremely regular timing for about 0.5 Gy. The regularity of the timing compared with earlier calculations of orbital perturbation would seem to exclude the Nemesis hypothesis as a causal factor.
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