发表机构
California Institute of Technology; Carnegie Science Observatories; Massachusetts Institute of Technology; Center for Astrophysics, Harvard & Smithsonian; University of Nebraska at Kearney; University of California Berkeley; University of California Santa Barbara（加州理工学院; 卡内基科学天文台; 麻省理工学院; 哈佛史密松天体物理中心; 内布拉斯加大学基尔尼分校; 加州大学伯克利分校; 加州大学圣塔芭芭拉分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对WASP-12 b的Keck观测发现凌星期间显著的Hα和Hβ吸收，证实其存在类似其他早型恒星行星的延伸氢外流，且外流气体溢出洛希瓣形成尾状结构。
AI 中文摘要
近期对围绕早型恒星运行的行星大气逃逸的观测表明，具有较高洛希瓣填充因子的行星具有显著更高的质量损失率。对于其中三颗行星，全轨道观测揭示了存在由逃逸行星物质构成的大型前导尾和尾随尾。这些三维外流几何结构编码了关于底层外流物理的信息，也可用于约束其恒星风特性并预测其长期轨道演化。我们为第四颗行星 WASP-12 b 提供了来自逃逸氢的延伸 Hα 和 Hβ 吸收的新证据。我们使用凯克 I 望远镜上的凯克行星探测器（Keck Planet Finder）在凌星前后约八小时的时段内观测了 WASP-12 b。我们在恒星静止参考系中发现了 Hα 和 Hβ 吸收信号，该信号在凌星期间最强（Hα 振幅：2.66±0.25%，Hβ 振幅：2.88±0.43%），并存在凌星前和凌星后吸收的证据。这一测量结果与外流模型一致，其中逃逸气体溢出行星的洛希瓣，并在被潮汐剪切形成延伸尾之前被平流输送到恒星静止参考系中。这种外流行为在性质上与此前对该行星的 Hα 观测以及围绕早型恒星运行的其他气态巨行星的延伸外流观测相似。
英文摘要
Recent observations of atmospheric escape from planets orbiting early-type stars indicate that planets with higher Roche filling factors have significantly higher mass loss rates. For three of these planets, full-orbit observations have revealed the presence of large leading and trailing tails of escaping planetary material. These 3D outflow geometries encode information about the underlying outflow physics, and can also be used to constrain their stellar wind properties and to predict their long-term orbital evolution. We present new evidence for extended H$α$ and H$β$ absorption from escaping hydrogen for a fourth planet, WASP-12 b. We observed WASP-12 b with the Keck Planet Finder on Keck I over a period of approximately eight hours centered on the transit. We find a H$α$ and H$β$ absorption signal in the stellar rest frame that is strongest during the transit (H$α$ amplitude: $2.66\pm0.25\%$, H$β$ amplitude: $2.88\pm0.43\%$), with evidence of both pre- and post-transit absorption. This measurement is consistent with outflow models where the escaping gas overflows the planet's Roche lobe and is advected into the stellar rest frame before being tidally sheared into extended tails. This outflow behavior is qualitatively similar to previous H$α$ observations of this planet as well as observations of extended outflows from other gas giants orbiting early-type stars.
Commentsaccepted in AJ
