论文标题
由大气逃生驱动的近距离地铁的轨道演变
Orbital Evolution of Close-in Super-Earths Driven by Atmospheric Escape
论文作者
论文摘要
越来越多的超级地铁靠近他们的主机恒星，在$ {\ it kepler} $行星的半径分布中，近距离的小行星的近距离小行星稀缺。通过光蒸发的超级地球的大气逃逸可以解释观察到的“半径间隙”的起源。许多理论研究考虑了近距离行星的原位质量损失。然而，经历大气的行星由于其星形行星系统的轨道角动量变化而向外移动。在这项研究中，我们计算出在恒星X射线和极端紫外线辐照（XUV）下，在FGKM型恒星周围使用H $ _2 $ _2 $/HE大气的渐射轨道演变。蒸发行星的轨道半径的增加速率与高恒星XUV相期间大气质量损失的速率大致成正比。 We show that super-Earths with a rocky core of $\lesssim$ 10$\,M_\oplus$ and a H$_2$/He atmosphere at $\lesssim$ 0.03-0.1$\,$au ($\lesssim$ 0.01-0.03$\,$au) around G-type stars (M-type stars) are prone to the outward migration driven通过光蒸发。尽管行星轨道的变化很小，但它们会重新排列紧凑的多个星光系统（例如Trappist-1系统）的轨道配置。我们还发现，在我们的模拟中，观察到的FGK型恒星周围观察到的近距离行星人口中的半径差距和所谓的“海王星沙漠”仍出现在我们的模拟中。另一方面，观测到的M型恒星周围的行星种群只能通过高出色的XUV光度模型来再现。
The increasing number of super-Earths close to their host stars revealed a scarcity of close-in small planets with 1.5-2.0$\,R_\oplus$ in the radius distribution of ${\it Kepler}$ planets. The atmospheric escape of super-Earths by photoevaporation can explain the origin of the observed "radius gap." Many theoretical studies considered the in-situ mass loss of a close-in planet. Planets that undergo the atmospheric escape, however, move outward due to the change in the orbital angular momentum of their star-planet systems. In this study, we calculate the orbital evolution of an evaporating super-Earth with a H$_2$/He atmosphere around FGKM-type stars under a stellar X-ray and extreme UV irradiation (XUV). The rate of increase in the orbital radius of an evaporating planet is approximately proportional to that of the atmospheric mass loss during a high stellar XUV phase. We show that super-Earths with a rocky core of $\lesssim$ 10$\,M_\oplus$ and a H$_2$/He atmosphere at $\lesssim$ 0.03-0.1$\,$au ($\lesssim$ 0.01-0.03$\,$au) around G-type stars (M-type stars) are prone to the outward migration driven by photoevaporation. Although the changes in the orbits of the planets would be small, they would rearrange the orbital configurations of compact, multi-planet systems, such as the TRAPPIST-1 system. We also find that the radius gap and the so-called "Neptune desert" in the observed population of close-in planets around FGK-type stars still appear in our simulations. On the other hand, the observed planet population around M-type stars can be reproduced only by a high stellar XUV luminosity model.
