The Dehydration of Water Worlds Via Atmospheric Losses

We present a three-species multi-fluid MHD model (H+, H2O+ and e−), endowed with the requisite atmospheric chemistry, that is capable of accurately quantifying the magnitude of water ion losses from exoplanets.

We apply this model to a water world with Earth-like parameters orbiting a Sun-like star for three cases: (i) current normal solar wind conditions, (ii) ancient normal solar wind conditions, and (iii) one extreme “Carrington-type” space weather event. We demonstrate that the ion escape rate for (ii), with a value of 6.0×1026 s−1, is about an order of magnitude higher than the corresponding value of 6.7×1025 s−1 for (i). Studies of ion losses induced by space weather events, where the ion escape rates can reach ∼ 1028 s−1, are crucial for understanding how an active, early solar-type star (e.g., with frequent coronal mass ejections) could have accelerated the depletion of the exoplanet’s atmosphere.

We briefly explore the ramifications arising from the loss of water ions, especially for planets orbiting M-dwarfs where such effects are likely to be significant.

Chuanfei Dong, Zhenguang Huang, Manasvi Lingam, Gábor Tóth, Tamas Gombosi, Amitava Bhattacharjee
(Submitted on 5 Sep 2017)

Comments: ApJ Letters, in press, 8 pages, 2 figures, 3 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
Cite as: arXiv:1709.01219 [astro-ph.EP] (or arXiv:1709.01219v1 [astro-ph.EP] for this version)
Submission history
From: Chuanfei Dong
[v1] Tue, 5 Sep 2017 02:50:43 GMT (1320kb)
https://arxiv.org/abs/1709.01219
Astrobiology