On the Orbital Variability of Ganymede's Atmosphere

Ganymede’s atmosphere is produced by radiative interactions with its surface, sourced by the Sun and the Jovian plasma. The sputtered and thermally desorbed molecules are tracked in our Exospheric Global Model (EGM), a 3-D parallelized collisional model.

This program was developed to reconstruct the formation of the upper atmosphere/exosphere of planetary bodies interacting with solar photon flux and magnetospheric and/or the solar wind plasmas. Here, we describe the spatial distribution of the H$_2$O and O2 components of Ganymede’s atmosphere, and their temporal variability along Ganymede’s rotation around Jupiter. In particular, we show that Ganymede’s O2 atmosphere is characterized by time scales of the order of Ganymede’s rotational period with Jupiter’s gravity being a significant driver of the spatial distribution of the heaviest exospheric components. Both the sourcing and the Jovian gravity are needed to explain some of the characteristics of the observed aurora emissions. As an example, the O2 exosphere should peak at the equator with systematic maximum at the dusk equator terminator. The sputtering rate of the H$_2$O exosphere should be maximum on the leading hemisphere because of the shape of the open/close field lines boundary and displays some significant variability with longitude.

Francois Leblanc, Apurva V. Oza, Ludivine Leclercq, Carl Schmidt, Timothy Cassidy, Ronan Modolo, Jean-Yves Chaufray, Robert E. Johnson
(Submitted on 27 Apr 2018)

Comments: 14 pages, 9 figures, Accepted to Icarus
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Journal reference: Icarus 2017, Volume 293, p. 185-198
DOI: 10.1016/j.icarus.2017.04.025
Cite as: arXiv:1804.10592 [astro-ph.EP] (or arXiv:1804.10592v1 [astro-ph.EP] for this version)
Submission history
From: Apurva Oza
[v1] Fri, 27 Apr 2018 17:05:47 GMT (1451kb)
https://arxiv.org/abs/1804.10592
Astrobiology