Structure of surface-H2O layers of ice-covered planets with high-pressure ice
Structure of surface-H2O layers of ice-covered planets with high-pressure ice
复制标题
高压冰覆盖的行星表面水层结构
DOI：
10.1088/0004-637x/775/2/96
复制
发表时间：
2013
影响因子：
4.9
通讯作者：
Takanori Sasaki
中科院分区：
文献类型：
--
作者：
Shoji Ueta;Takanori Sasaki
已发现许多太阳系外（束缚）类地行星和自由漂浮（未束缚）行星。虽然有液态水的束缚和非束缚类地行星的存在是一个重要问题，但特别重要的是这些行星的宜居性问题。即使对于全球被冰覆盖的行星，来自行星内部的地热也可能融化内部冰，形成被冰壳覆盖的内部海洋。在本文中，我们讨论了类地行星在行星演化的时间尺度上必须满足这样的内部海洋存在的条件。这个问题是根据行星质量、距中心恒星的距离、水丰度和放射热源丰度来解决的。此外，我们通过考虑高压下冰（高压冰）的影响来研究被冰覆盖的行星表面H 2 O层的结构。作为一个基准案例，一颗距离其中心恒星 1 个天文单位、质量为地球 H 2 O 0.6-25 倍的 1 M⊕ 行星可能拥有内部海洋。我们发现，在一颗H 2 O质量超过地球25倍的行星上，其内部海洋和岩石部分之间可能会出现高压冰层。行星质量和地表水丰度极大地限制了太阳系外类地行星可能拥有内部海洋且海洋下没有高压冰的条件。内海下方的这种高压冰层可能会影响地球的宜居性。
Many extrasolar (bound) terrestrial planets and free-floating (unbound) planets have been discovered. While the existence of bound and unbound terrestrial planets with liquid water is an important question, of particular importance is the question of these planets' habitability. Even for a globally ice-covered planet, geothermal heat from the planetary interior may melt the interior ice, creating an internal ocean covered by an ice shell. In this paper, we discuss the conditions that terrestrial planets must satisfy for such an internal ocean to exist on the timescale of planetary evolution. The question is addressed in terms of planetary mass, distance from a central star, water abundance, and abundance of radiogenic heat sources. In addition, we investigate the structure of the surface H 2 O layers of ice-covered planets by considering the effects of ice under high pressure (high-pressure ice). As a fiducial case, a 1 M⊕ planet at 1 AU from its central star and with 0.6–25 times the H 2 O mass of the Earth could have an internal ocean. We find that high-pressure ice layers may appear between the internal ocean and the rock portion on a planet with an H 2 O mass over 25 times that of the Earth. The planetary mass and abundance of surface water strongly restrict the conditions under which an extrasolar terrestrial planet may have an internal ocean with no high-pressure ice under the ocean. Such high-pressure ice layers underlying the internal ocean are likely to affect the habitability of the planet.