MASS-LOSS EVOLUTION OF CLOSE-IN EXOPLANETS: EVAPORATION OF HOT JUPITERS AND THE EFFECT ON POPULATION
MASS-LOSS EVOLUTION OF CLOSE-IN EXOPLANETS: EVAPORATION OF HOT JUPITERS AND THE EFFECT ON POPULATION
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DOI：
10.1088/0004-637x/783/1/54
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发表时间：
2014-01
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影响因子：
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通讯作者：
Hiroyuki Kurokawa;Taishi Nakamoto Nagoya University;Tokyo Institute of Technology
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作者：
Hiroyuki Kurokawa;Taishi Nakamoto Nagoya University;Tokyo Institute of Technology
在其演化过程中，短周期系外行星可能会因来自其主恒星的强烈 X 射线和极紫外 (XUV) 辐射而逃逸大气而失去包层质量。由轨道演化或强烈的大气逃逸引起的罗希瓣溢出也会导致质量损失。为了研究质量损失对内行星种群的影响，我们考虑了其包层的质量损失和热收缩来计算热木星的演化。假设质量损失是通过 XUV 驱动的大气逃逸和随后的罗希瓣溢出而发生的。质量损失的失控效应导致了人口的二分法：保留其外壳的热木星和外壳完全丢失的超级地球。进化主要取决于行星的核心质量，仅少量取决于迁移历史。在具有小核心（≃ 10 个地球质量）的热木星中，失控的大气逃逸以及随后的罗希瓣溢出可能会形成木星以下的沙漠，正如在行星种群的质量和半径分布中所观察到的那样。将我们的结果与形成情景和观测到的系外行星种群进行比较，我们提出，紧密绕轨道运行的系外行星种群是通过捕获原行星盘内边缘/内部边缘的行星以及随后的亚木星蒸发而形成的。
During their evolution, short-period exoplanets may lose envelope mass through atmospheric escape owing to intense X-ray and extreme ultraviolet (XUV) radiation from their host stars. Roche-lobe overflow induced by orbital evolution or intense atmospheric escape can also contribute to mass loss. To study the effects of mass loss on inner planet populations, we calculate the evolution of hot Jupiters considering mass loss of their envelopes and thermal contraction. Mass loss is assumed to occur through XUV-driven atmospheric escape and the following Roche-lobe overflow. The runaway effect of mass loss results in a dichotomy of populations: hot Jupiters that retain their envelopes and super Earths whose envelopes are completely lost. Evolution primarily depends on the core masses of planets and only slightly on migration history. In hot Jupiters with small cores (≃ 10 Earth masses), runaway atmospheric escape followed by Roche-lobe overflow may create sub-Jupiter deserts, as observed in both mass and radius distributions of planetary populations. Comparing our results with formation scenarios and observed exoplanets populations, we propose that populations of closely orbiting exoplanets are formed by capturing planets at/inside the inner edges of protoplanetary disks and subsequent evaporation of sub-Jupiters.