Thermal-Orbital Coupled Tidal Heating and Habitability of Martian-Sized Extrasolar Planets around M Stars
Thermal-Orbital Coupled Tidal Heating and Habitability of Martian-Sized Extrasolar Planets around M Stars
复制标题
M 星周围火星大小的太阳系外行星的热轨道耦合潮汐加热和宜居性
DOI：
10.1088/0004-637x/789/1/3
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发表时间：
2014
影响因子：
4.9
通讯作者：
K. Kurita
中科院分区：
文献类型：
--
作者：
D. Shoji;K. Kurita
M型恒星是寻找宜居系外行星的良好目标。由于有效温度较低，M星的宜居带非常接近恒星本身。对于距离恒星较近的行星，潮汐加热在热演化和轨道演化中起着重要作用，特别是当行星轨道偏心率较大时。尽管潮汐加热与行星的热状态和轨道相互作用，但尚未对 M 星周围的太阳系外行星进行这种耦合计算。我们使用简单的结构和轨道模型进行耦合计算，并分析类地行星的热状态和宜居性。考虑到这颗行星的大小与火星相当，如果恒星的质量小于太阳质量的 0.2 倍且轨道的初始偏心率大于 0.2，则潮汐会升温并部分熔化地幔，从而保持平衡状态。地幔融化导致的散热减少，使得行星即使轨道距离很短，仍能在宜居带停留超过10吉里。平衡状态下的表面热通量介于火星和木卫一之间。行星的热状态主要取决于偏心率的初始值和恒星的质量。
M-type stars are good targets in the search for habitable extrasolar planets. Due to their low effective temperatures, the habitable zone of M stars is very close to the stars themselves. For planets that are close to their stars, tidal heating plays an important role in thermal and orbital evolutions, especially when the planet's orbit has a relatively large eccentricity. Although tidal heating interacts with the thermal state and the orbit of the planet, such coupled calculations for extrasolar planets around M stars have not been conducted. We perform coupled calculations using simple structural and orbital models and analyze the thermal state and habitability of a terrestrial planet. Considering this planet to be Martian-sized, the tide heats up and partially melts the mantle, maintaining an equilibrium state if the mass of the star is less than 0.2 times the mass of the Sun and the initial eccentricity of the orbit is more than 0.2. The reduction of heat dissipation due to the melted mantle allows the planet to stay in the habitable zone for more than 10 Gyr even though the orbital distance is small. The surface heat flux at the equilibrium state is between that of Mars and Io. The thermal state of the planet mainly depends on the initial value of the eccentricity and the mass of the star.