ATMOSPHERE-INTERIOR EXCHANGE ON HOT, ROCKY EXOPLANETS
ATMOSPHERE-INTERIOR EXCHANGE ON HOT, ROCKY EXOPLANETS
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DOI：
10.3847/0004-637x/828/2/80
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发表时间：
2016-06
期刊：
影响因子：
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通讯作者：
E. Kite;B. Fegley;L. Schaefer;E. Gaidos
中科院分区：
文献类型：
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作者：
E. Kite;B. Fegley;L. Schaefer;E. Gaidos
我们提供了对具有日侧岩浆池和硅酸盐蒸气大气的短周期岩石系外行星的大气压力和表面成分的估计。大气压力与地表岩浆趋于蒸气-压力平衡，岩浆-地表成分由分馏汽化和地表-内部交换的竞争效应决定。我们使用基本模型来展示表面-内部交换是如何受到行星的温度、质量和初始组成的控制的。我们假设地幔岩石经历大量熔融形成岩浆池，风从星下点径向流动。根据这些假设，我们发现：(1)当行星的块状硅酸盐FeO浓度较低时，大气-内部交换是快速的，而当行星的块状硅酸盐FeO浓度较高时，大气-内部交换是缓慢的；(2)对于星下温度≲2400K，岩浆池的成分混合得很好，但成分多样化，并且随着星下温度≳2400K的变化而迅速变化；(3)岩浆池内的洋流倾向于冷却固体地幔的顶部(“构造制冷”)；(4)与以前的工作相反，许多岩浆行星的表面成分是时变的。
We provide estimates of atmospheric pressure and surface composition on short-period, rocky exoplanets with dayside magma pools and silicate-vapor atmospheres. Atmospheric pressure tends toward vapor-pressure equilibrium with surface magma, and magma-surface composition is set by the competing effects of fractional vaporization and surface-interior exchange. We use basic models to show how surface-interior exchange is controlled by the planet’s temperature, mass, and initial composition. We assume that mantle rock undergoes bulk melting to form the magma pool, and that winds flow radially away from the substellar point. With these assumptions, we find that: (1) atmosphere-interior exchange is fast when the planet’s bulk-silicate FeO concentration is low, and slow when the planet’s bulk-silicate FeO concentration is high; (2) magma pools are compositionally well mixed for substellar temperatures ≲2400 K, but compositionally variegated and rapidly variable for substellar temperatures ≳2400 K; (3) currents within the magma pool tend to cool the top of the solid mantle (“tectonic refrigeration”); (4) contrary to earlier work, many magma planets have time-variable surface compositions.