文章基本信息

标题：Young planets under extreme UV irradiation
其他标题：I. Upper atmosphere modelling of the young exoplanet K2-33b
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作者：D. Kubyshkina ; M. Lendl ; L. Fossati 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：612
DOI：10.1051/0004-6361/201731816
语种：English
出版社：EDP Sciences
摘要：The K2-33 planetary system hosts one transiting ~5R⊕planet orbiting the young M-type host star. The planet’s mass is still unknown, with an estimated upper limit of 5.4MJ. The extreme youth of the system (<20 Myr) gives the unprecedented opportunity to study the earliest phases of planetary evolution, at a stage when the planet is exposed to an extremely high level of high-energy radiation emitted by the host star. We perform a series of 1D hydrodynamic simulations of the planet’s upper atmosphere considering a range of possible planetary masses, from 2 to 40M⊕, and equilibrium temperatures, from 850 to 1300 K, to account for internal heating as a result of contraction. We obtain temperature profiles mostly controlled by the planet’s mass, while the equilibrium temperature has a secondary effect. For planetary masses below 7–10M⊕, the atmosphere is subject to extremely high escape rates, driven by the planet’s weak gravity and high thermal energy, which increase with decreasing mass and/or increasing temperature. For higher masses, the escape is instead driven by the absorption of the high-energy stellar radiation. A rough comparison of the timescales for complete atmospheric escape and age of the system indicates that the planet is more massive than 10M⊕.
关键词：Key wordsenstars: low massstars: late typeplanets and satellites: general