Measuring the melting curve of iron at super-Earth core conditions
Measuring the melting curve of iron at super-Earth core conditions
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DOI：
10.1126/science.abm1472
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发表时间：
2022-01-14
期刊：
影响因子：
56.9
通讯作者：
Eggert, Jon H.
中科院分区：
文献类型：
--
作者：
Kraus, Richard G.;Hemley, Russell J.;Eggert, Jon H.
超过4500颗太阳系外行星的发现，产生了对它们内部结构和动力学建模的需求。考虑到铁在行星内部的重要性，我们需要在极端压力和温度下准确和精确的物理性质。铁的一级性质是它的熔点，这仍然是地球内部条件的争论。我们在国家点火装置上使用了高能激光和原位X射线衍射来确定铁的熔点高达1000吉帕斯卡，是地球内核压力的三倍。我们使用此熔化曲线来确定在核心凝固到六方密堆积（hcp）结构期间发电机作用的长度。我们发现，质量是地球四到六倍的类地系外行星具有最长的发电机，这为宇宙辐射提供了重要的屏蔽。
The discovery of more than 4500 extrasolar planets has created a need for modeling their interior structure and dynamics. Given the prominence of iron in planetary interiors, we require accurate and precise physical properties at extreme pressure and temperature. A first-order property of iron is its melting point, which is still debated for the conditions of Earth's interior. We used high-energy lasers at the National Ignition Facility and in situ x-ray diffraction to determine the melting point of iron up to 1000 gigapascals, three times the pressure of Earth's inner core. We used this melting curve to determine the length of dynamo action during core solidification to the hexagonal close-packed (hcp) structure. We find that terrestrial exoplanets with four to six times Earth's mass have the longest dynamos, which provide important shielding against cosmic radiation.