论文标题
几百万年前，太阳系通过冷云通过的陆地影响
Terrestrial Impact from the Passage of the Solar System through a Cold Cloud a Few Million Years Ago
论文作者
论文摘要
可以预期，随着太阳通过星际介质（ISM）行进，影响地球的银河宇宙射线（GCR）将会有不同的过滤。 GCR对地球大气和气候的影响仍然不确定。尽管先前考虑了与分子云的相互作用，但紧凑型冷云的地面影响被忽略了。有大量的地质证据来自60FE和244PU同位素，表明地球直接与200万年前的ISM接触，而当地的ISM是附近几个寒冷云的所在地。在这里，我们展示了一个最先进的模拟，结合了有关地球球的所有当前知识，如果太阳系通过云层（例如当地的Leo Cold Cloud），那么保护太阳系免受星际粒子的范围的地球球层必须将其缩小到比太阳周围的地球轨道小（0.22）缩小的比例（0.22）。使用包括中性原子和离子之间的电荷交换的磁流体动力模拟，我们表明在地球层收缩期间，地球暴露于中性氢密度最高为3000cm-3。正如现有数据所暗示的那样，这可能会对地球的气候产生巨大影响，并可能对当时的人类进化产生巨大影响。
It is expected that as the Sun travels through the interstellar medium (ISM), there will be different filtration of Galactic Cosmic Rays (GCR) that affect Earth. The effect of GCR on Earth's atmosphere and climate is still uncertain. Although the interaction with molecular clouds was previously considered, the terrestrial impact of compact cold clouds was neglected. There is overwhelming geological evidence from 60Fe and 244Pu isotopes that Earth was in direct contact with the ISM 2 million years ago, and the local ISM is home to several nearby cold clouds. Here we show, with a state-of the art simulation that incorporate all the current knowledge about the heliosphere that if the solar system passed through a cloud such as Local Leo Cold Cloud, then the heliosphere which protects the solar system from interstellar particles, must have shrunk to a scale smaller than the Earth's orbit around the Sun (0.22). Using a magnetohydrodynamic simulation that includes charge exchange between neutral atoms and ions, we show that during the heliosphere shrinkage, Earth was exposed to a neutral hydrogen density of up to 3000cm-3. This could have had drastic effects on Earth's climate and potentially on human evolution at that time, as suggested by existing data.
