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arXiv 2005.13190astro-ph.EPastro-ph.SRphysics.space-ph
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从TOI-700 d大气逃逸：金星与地球类似物

Atmospheric Escape From TOI-700 d: Venus versus Earth Analogs

Chuanfei Dong, Meng Jin, Manasvi Lingam

备注：
ApJ Letters, in press, 8 pages, 3 figures, and 1 table
发表信息：
The Astrophysical Journal Letters, Vol. 896, L24 (2020)
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摘要：

凌日系外行星勘测卫星最近在一颗早期M矮星的宜居带发现了一颗地球大小的行星（TOI-700 d），这是一项重要进展。在这封信中，我们评估了这颗行星保留大气层的可行性-表面可居住性的主要成分之一-通过采用最先进的磁流体动力学模型来模拟恒星风和相关的大气逃逸率。我们考虑两个主要因素，即行星大气成分和磁场。在所有情况下，我们确定大气离子逃逸率可能比内太阳系行星高几个数量级，但TOI-700 d仍然能够在参数空间的某些区域保持$1$ bar大气超过千兆年的时间尺度。模拟结果表明，未磁化的TOI-700 d与1巴类地大气可以剥离得相当快（$<$ 1千兆年），而未磁化的TOI-700 d与1巴CO $_2$为主的大气可以持续数十亿年;我们发现，磁化类地的情况下，这两种情况之间的下降。我们还讨论了探测行星无线电发射（从而限制其磁场）和辨别大气层存在的前景。

英文摘要：

The recent discovery of an Earth-sized planet (TOI-700 d) in the habitable zone of an early-type M-dwarf by the Transiting Exoplanet Survey Satellite constitutes an important advance. In this Letter, we assess the feasibility of this planet to retain an atmosphere -- one of the chief ingredients for surface habitability -- over long timescales by employing state-of-the-art magnetohydrodynamic models to simulate the stellar wind and the associated rates of atmospheric escape. We take two major factors into consideration, namely, the planetary atmospheric composition and magnetic field. In all cases, we determine that the atmospheric ion escape rates are potentially a few orders of magnitude higher than the inner Solar system planets, but TOI-700 d is nevertheless capable of retaining a $1$ bar atmosphere over gigayear timescales for certain regions of the parameter space. The simulations show that the unmagnetized TOI-700 d with a 1 bar Earth-like atmosphere could be stripped away rather quickly ($<$ 1 gigayear), while the unmagnetized TOI-700 d with a 1 bar CO$_2$-dominated atmosphere could persist for many billions of years; we find that the magnetized Earth-like case falls in between these two scenarios. We also discuss the prospects for detecting radio emission of the planet (thereby constraining its magnetic field) and discerning the presence of an atmosphere.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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