On the orbital variability of Ganymede's atmosphere

Abstract

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 O${}_2$ components of Ganymede's atmosphere, and their temporal variability along Ganymede's rotation around Jupiter. In particular, we show that Ganymede's O${}_2$ 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 O${}_2$ 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.

arXiv comment14 pages, 9 figures, Accepted to Icarus

References in corpus (2)

• HST/STIS Ultraviolet Imaging of Polar Aurora on Ganymede
• Precipitation of Energetic Neutral Atoms and Induced Non-Thermal Escape Fluxes from the Martian Atmosphere

Cited by in corpus (14)

• A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations
• Composition and thermal properties of Ganymede's surface from JWST/NIRSpec and MIRI observations
• Dusk Over Dawn O${}_2$ Asymmetry in Europa's Near-Surface Atmosphere
• The Optical Aurorae of Europa, Ganymede and Callisto
• Callisto's atmosphere: First evidence for H2 and constraints on H2O
• A tenuous, collisional atmosphere on Callisto
• The origin and fate of O${}_2$ in Europa's ice: an atmospheric perspective
• Electron Impact Ionization in the Icy Galilean Satellites' Atmospheres
• Mapping the Brightness of Ganymede's Ultraviolet Aurora using Hubble Space Telescope Observations
• A patchy CO${}_2$ exosphere on Ganymede revealed by the James Webb Space Telescope
• Probing Ganymede's atmosphere with HST Ly$\alpha$ images in transit of Jupiter
• Short-Timescale Spatial Variability of Ganymede's Optical Aurora
• The influence of upper boundary conditions on molecular kinetic atmospheric escape simulations
• Constraining Electron-Impact Ionization of O${}_2$ Through UV Aurora Observations at Ganymede