Universität zu Köln

Roth, Lorenz ORCID: 0000-0003-0554-4691, Ivchenko, Nickolay ORCID: 0000-0003-2422-5426, Gladstone, G. Randall, Saur, Joachim, Grodent, Denis ORCID: 0000-0002-9938-4707, Bonfond, Bertrand ORCID: 0000-0002-2514-0187, Molyneux, Philippa M. and Retherford, Kurt D. (2021). A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations. Nat. Astron., 5 (10). S. 1043 - 1055. BERLIN: NATURE PORTFOLIO. ISSN 2397-3366

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Abstract

Ganymede's atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the O i 1,356 A and O i 1,304 A oxygen emissions were used to infer sputtered molecular oxygen (O-2) as an atmospheric constituent, but an expected sublimated water (H2O) component remained undetected. Here we present an analysis of high-sensitivity spectra and spectral images acquired by the Hubble Space Telescope revealing H2O in Ganymede's atmosphere. The relative intensity of the oxygen emissions requires contributions from the dissociative excitation of water vapour, indicating that H2O is more abundant than O-2 around the subsolar point. Away from the subsolar region, the emissions are consistent with a pure O-2 atmosphere. Eclipse observations constrain atomic oxygen to be at least two orders of magnitude less abundant than these other species. The higher H2O/O-2 ratio above the warmer trailing hemisphere compared with the colder leading hemisphere, the spatial concentration in the subsolar region and the estimated abundance of similar to 10(15) molecules of H2O per cm(2) are consistent with sublimation of the icy surface as source.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Roth, Lorenz UNSPECIFIED orcid.org/0000-0003-0554-4691 UNSPECIFIED Ivchenko, Nickolay UNSPECIFIED orcid.org/0000-0003-2422-5426 UNSPECIFIED Gladstone, G. Randall UNSPECIFIED UNSPECIFIED UNSPECIFIED Saur, Joachim UNSPECIFIED UNSPECIFIED UNSPECIFIED Grodent, Denis UNSPECIFIED orcid.org/0000-0002-9938-4707 UNSPECIFIED Bonfond, Bertrand UNSPECIFIED orcid.org/0000-0002-2514-0187 UNSPECIFIED Molyneux, Philippa M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Retherford, Kurt D. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-585218
DOI:	10.1038/s41550-021-01426-9
Journal or Publication Title:	Nat. Astron.
Volume:	5
Number:	10
Page Range:	S. 1043 - 1055
Date:	2021
Publisher:	NATURE PORTFOLIO
Place of Publication:	BERLIN
ISSN:	2397-3366
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language OXYGEN ATMOSPHERE; CROSS-SECTIONS; ELECTRON-IMPACT; ATOMIC OXYGEN; AURORA; HYDROGEN; HST/STIS; SURFACE; H2O; CONSTRAINTS Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/58521