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The influence of Europa's plumes on its atmosphere and ionosphere

Li, Jiazheng and Gudipati, Murthy S. and Yung, Yuk L. (2020) The influence of Europa's plumes on its atmosphere and ionosphere. Icarus, 352 . Art. No. 113999. ISSN 0019-1035. https://resolver.caltech.edu/CaltechAUTHORS:20200818-073830104

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Abstract

Europa, one of the Galilean satellites, has a tenuous, oxygen-dominated atmosphere that is usually referred to as a collision-less exosphere. Coupled to the neutral atmosphere and in contact with Europa's surface, a tenuous ionosphere exists on Europa, whose presence has been revealed by multiple observations. Such an ionosphere is thought to be produced by solar photoionization and electron-impact ionization of the oxygen in the atmosphere. However, a recent study showed that the maximum ionosphere coincides with intermittent water plume on Europa, suggesting that water plays an important role in the formation of the ionosphere. Based on the assumption of horizontal uniformity in the middle of the plume, we use the Caltech/Jet Propulsion Laboratory one-dimensional KINETICS model to construct profiles of neutral and ionized species near the plume region. The simulation results, which show that the ionization reactions are initiated by water electron-impact ionization and photoionization and continued by charge transfer between water and oxygen molecules, have successfully reproduced the observations. We find that H₂O⁺ is the dominant species only above the ionopause. Below the ionopause, the density of H₂O⁺ is orders of magnitude lower than the density of O₂⁺, which is the major composition below the ionopause. Our model has also been used to study the dissociation processes of water molecules from the plumes, which can be regarded as an alternative source for the oxygen in the atmosphere.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.icarus.2020.113999DOIArticle
ORCID:
AuthorORCID
Gudipati, Murthy S.0000-0001-5992-373X
Yung, Yuk L.0000-0002-4263-2562
Additional Information:© 2020 Elsevier Inc. Received 6 November 2019, Revised 21 July 2020, Accepted 21 July 2020, Available online 27 July 2020. We thank D. Shemansky for useful discussions. This research was supported in part by an NSF grant to Caltech. MSG thanks JPL for support through the JPL-Campus JROC program. Declaration of Competing Interest: None.
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Record Number:CaltechAUTHORS:20200818-073830104
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200818-073830104
Official Citation:Jiazheng Li, Murthy S. Gudipati, Yuk L. Yung, The influence of Europa's plumes on its atmosphere and ionosphere, Icarus, Volume 352, 2020, 113999, ISSN 0019-1035, https://doi.org/10.1016/j.icarus.2020.113999. (http://www.sciencedirect.com/science/article/pii/S001910352030364X)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104988
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 Aug 2020 15:29
Last Modified:18 Aug 2020 15:29

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