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Title: The Dehydration of Water Worlds via Atmospheric Losses

Abstract

Here, we present a three-species multi-fluid magnetohydrodynamic model (H +, H 2O +, 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 × 10 26 s –1, is about an order of magnitude higher than the corresponding value of 6.7 × 10 25 s –1 for (i). Studies of ion losses induced by space weather events, where the ion escape rates can reach ~10 28 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.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Princeton Univ., Princeton, NJ (United States). Dept. of Astrophysical Sciences and Princeton Plasma Physics Lab.
  2. Univ. of Michigan, Ann Arbor, MI (United States). Center for Space and Environment Modeling
  3. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Harvard Univ., Cambridge, MA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1420423
Grant/Contract Number:
GS-1338944 and AGS-1552142
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 847; Journal Issue: 1; Journal ID: ISSN 2041-8213
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; astrobiology; magnetohydrodynamics (MHD); planets and satellites: atmospheres; planets and satellites: magnetic fields; planets and satellites: physical evolution; planets and satellites: terrestrial planets

Citation Formats

Dong, Chuanfei, Huang, Zhenguang, Lingam, Manasvi, Toth, Gabor, Gombosi, Tamas, and Bhattacharjee, Amitava. The Dehydration of Water Worlds via Atmospheric Losses. United States: N. p., 2017. Web. doi:10.3847/2041-8213/aa8a60.
Dong, Chuanfei, Huang, Zhenguang, Lingam, Manasvi, Toth, Gabor, Gombosi, Tamas, & Bhattacharjee, Amitava. The Dehydration of Water Worlds via Atmospheric Losses. United States. doi:10.3847/2041-8213/aa8a60.
Dong, Chuanfei, Huang, Zhenguang, Lingam, Manasvi, Toth, Gabor, Gombosi, Tamas, and Bhattacharjee, Amitava. Thu . "The Dehydration of Water Worlds via Atmospheric Losses". United States. doi:10.3847/2041-8213/aa8a60.
@article{osti_1420423,
title = {The Dehydration of Water Worlds via Atmospheric Losses},
author = {Dong, Chuanfei and Huang, Zhenguang and Lingam, Manasvi and Toth, Gabor and Gombosi, Tamas and Bhattacharjee, Amitava},
abstractNote = {Here, we present a three-species multi-fluid magnetohydrodynamic 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.},
doi = {10.3847/2041-8213/aa8a60},
journal = {The Astrophysical Journal. Letters},
number = 1,
volume = 847,
place = {United States},
year = {Thu Sep 14 00:00:00 EDT 2017},
month = {Thu Sep 14 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on September 14, 2018
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Cited by: 2 works
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