Universität zu Köln

Marzok, A., Schlegel, S., Saur, J., Roth, L., Grodent, D., Strobel, D. F. and Retherford, K. D. (2022). Mapping the Brightness of Ganymede's Ultraviolet Aurora Using Hubble Space Telescope Observations. J. Geophys. Res.-Planets, 127 (6). WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9100

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Abstract

We analyze Hubble Space Telescope observations of Ganymede made with the Space Telescope Imaging Spectrograph between 1998 and 2017 to generate a brightness map of Ganymede's oxygen emission at 1,356 angstrom. Our Mercator projected map demonstrates that the brightness along Ganymede's northern and southern auroral ovals strongly varies with longitude. To quantify this variation around Ganymede, we investigate the brightness averaged over 36 degrees-wide longitude corridors centered around the sub-Jovian (0 degrees W), leading (90 degrees W), anti-Jovian (180 degrees W), and trailing (270 degrees W) central longitudes. In the northern hemisphere, the brightness of the auroral oval is 3.7 +/- 0.4 times lower in the sub-Jovian and anti-Jovian corridors compared to the trailing and leading corridors. The southern oval is overall brighter than the northern oval, and only 2.5 +/- 0.2 times fainter on the sub- and anti-Jovian corridors compared to the trailing and leading corridors. This demonstrates that Ganymede's auroral ovals are strongly structured in auroral crescents on the leading side (plasma downstream side) and on the trailing side (plasma upstream side). We also find that the brightness is not symmetric with respect to the 270 degrees meridian, but shifted by similar to 20 degrees towards the Jovian-facing hemisphere. Our map will be useful for subsequent studies to understand the processes that generate the aurora in Ganymede's non-rotationally driven, sub-Alfvenic magnetosphere.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Marzok, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schlegel, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Saur, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Roth, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Grodent, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Strobel, D. F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Retherford, K. D. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-686078
DOI:	10.1029/2022JE007256
Journal or Publication Title:	J. Geophys. Res.-Planets
Volume:	127
Number:	6
Date:	2022
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-9100
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language HST/STIS; MODEL; SIMULATION; EMISSIONS; BOUNDARY Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/68607