Stellar wind effect on the atmospheric escape of hot Jupiters and their Lyα and Hα transits
Stellar wind effect on the atmospheric escape of hot Jupiters and their Lyα and Hα transits
复制标题
恒星风对热木星大气逃逸及其 Lyα 和 Hα 凌日的影响
DOI：
10.1093/mnras/stac556
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发表时间：
2022
影响因子：
4.8
通讯作者：
Yoshida Naoki
中科院分区：
文献类型：
--
作者：
Mitani Hiroto;Nakatani Riouhei;Yoshida Naoki
近距离系外行星的大气逃逸可能是由主恒星的高能辐射驱动的。行星流出与恒星风相互作用可能会产生可观察到的凌日信号，这取决于恒星风的强度。我们对热木星的大气逃逸进行了详细的辐射-流体力学模拟，其中包括了来自主星的风，以自洽的、动态耦合的方式。我们发现行星外流是由它的热压和恒星风的冲压之间的平衡形成的。我们使用仿真输出来计算莱曼α和H α过境签名。大风可以限制外流，减小莱曼α过境深度。相比之下，风对H α的影响很小，因为地球最上面的大气层贡献很小。观察这两个品系对于了解来自寄主的紫外线辐射和风的影响很重要。大气质量损失率大致与风力大小无关。我们还讨论了日冕物质抛射对签名的影响。我们认为，在M附近，矮星的影响可能在每一次凌日中都是显著的。
Atmospheric escape of close-in exoplanets can be driven by high-energy radiation from the host star. The planetary outflows interacting with the stellar wind may generate observable transit signals that depend on the strength of the stellar wind. We perform detailed radiation-hydrodynamics simulations of the atmospheric escape of hot Jupiters with including the wind from the host star in a self-consistent, dynamically coupled manner. We show that the planetary outflow is shaped by the balance between its thermal pressure and the ram pressure of the stellar wind. We use the simulation outputs to calculate the Lyman α and H α transit signatures. Strong winds can confine the outflow and decrease the Lyman α transit depth. Contrastingly, the wind effect on H α is weak because of the small contribution from the uppermost atmosphere of the planet. Observing both of the lines is important to understand the effect of the ultraviolet radiation and wind from the host. The atmospheric mass-loss rate is approximately independent of the strength of the wind. We also discuss the effect of the coronal mass ejections on the signatures. We argue that around M dwarfs the effect can be significant in every transit.