论文标题

系外星次要气氛损失和复兴

Exoplanet secondary atmosphere loss and revival

论文作者

Kite, Edwin S., Barnett, Megan

论文摘要

通往另一个地球的路径的下一步是在岩石系外行星上找到类似于地球和金星的气氛 - 高分子 - 体重(次要)气氛。许多岩石系外行星天生有厚(> 10 kbar)h $ _2 $ dominations的气氛,但随后失去了h $ _2 $;这个过程没有已知的太阳系类似物。我们研究了使用简单的大气进化模型(包括空间损失,岩浆海洋结晶和火山量表),我们研究了厚H $ _2 $大气的早期损失的后果。我们还计算了岩石世界的氛围生存,这些岩石世界以无h $ _2 $开头。我们的结果表明,大多数岩石系外行星比以较厚的h $ _2 $区的气氛形成的可居住区更接近其恒星,而当今的大气层则缺乏高分子量的大气。在早期的岩浆海洋结晶期间,高分子重量物种通常不会形成长期寿命的高分子重量大气。相反,它们与h $ _2 $一起丢失到空间。这种早期的挥发性耗竭也使后来的火山升起更难复兴大气。但是,气氛应该持续到从大量挥发物开始的世界上(例如,水世界)。我们的结果表明,为了在旋转M-Star的温暖系外星球上找到高分子重量的气氛,我们应该针对形成h $ _2 $ to-poor的世界,这些世界异常大的半径或轨道较小的恒星。

The next step on the path toward another Earth is to find atmospheres similar to those of Earth and Venus - high-molecular-weight (secondary) atmospheres - on rocky exoplanets. Many rocky exoplanets are born with thick (> 10 kbar) H$_2$-dominated atmospheres but subsequently lose their H$_2$; this process has no known Solar System analog. We study the consequences of early loss of a thick H$_2$ atmosphere for subsequent occurrence of a high-molecular-weight atmosphere using a simple model of atmosphere evolution (including atmosphere loss to space, magma ocean crystallization, and volcanic outgassing). We also calculate atmosphere survival for rocky worlds that start with no H$_2$. Our results imply that most rocky exoplanets orbiting closer to their star than the Habitable Zone that were formed with thick H$_2$-dominated atmospheres lack high-molecular-weight atmospheres today. During early magma ocean crystallization, high-molecular-weight species usually do not form long-lived high-molecular-weight atmospheres; instead they are lost to space alongside H$_2$. This early volatile depletion also makes it more difficult for later volcanic outgassing to revive the atmosphere. However, atmospheres should persist on worlds that start with abundant volatiles (for example, waterworlds). Our results imply that in order to find high-molecular-weight atmospheres on warm exoplanets orbiting M-stars, we should target worlds that formed H$_2$-poor, that have anomalously large radii, or which orbit less active stars.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源