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The composition and structure of the Enceladus plume

Hansen, C J; Shemansky, Donald E; Esposito, Larry W.; Stewart, A I F; Lewis, Brenton; Colwell, J E; Hendrix, A R; West, Robert A; Waite, J H; Teolis, B; Magee, B A

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The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed an occultation of the Sun by the water vapor plume at the south polar region of Saturn's moon Enceladus. The Extreme Ultraviolet (EUV) spectrum is dominated by the spectral signature of H2O gas, with a nominal line-of-sight column density of 0.90 0.23 × 1016 cm-2 (upper limit of 1.0 × 1016 cm-2). The upper limit for N2 is 5 × 1013 cm-2, or <0.5% in the plume; the lack of N2 has significant implications for models of the geochemistry...[Show more]

dc.contributor.authorHansen, C J
dc.contributor.authorShemansky, Donald E
dc.contributor.authorEsposito, Larry W.
dc.contributor.authorStewart, A I F
dc.contributor.authorLewis, Brenton
dc.contributor.authorColwell, J E
dc.contributor.authorHendrix, A R
dc.contributor.authorWest, Robert A
dc.contributor.authorWaite, J H
dc.contributor.authorTeolis, B
dc.contributor.authorMagee, B A
dc.date.accessioned2015-12-10T23:32:28Z
dc.identifier.issn0094-8276
dc.identifier.urihttp://hdl.handle.net/1885/68850
dc.description.abstractThe Cassini Ultraviolet Imaging Spectrograph (UVIS) observed an occultation of the Sun by the water vapor plume at the south polar region of Saturn's moon Enceladus. The Extreme Ultraviolet (EUV) spectrum is dominated by the spectral signature of H2O gas, with a nominal line-of-sight column density of 0.90 0.23 × 1016 cm-2 (upper limit of 1.0 × 1016 cm-2). The upper limit for N2 is 5 × 1013 cm-2, or <0.5% in the plume; the lack of N2 has significant implications for models of the geochemistry in Enceladus' interior. The inferred rate of water vapor injection into Saturn's magnetosphere is ∼200 kg/s. The calculated values of H2O flux from three occultations observed by UVIS have a standard deviation of 30 kg/s (15%), providing no evidence for substantial short-term variability. Collimated gas jets are detected in the plume with Mach numbers of 5-8, implying vertical gas velocities that exceed 1000 m/sec. Observations at higher altitudes with the Cassini Ion Neutral Mass Spectrometer indicate correlated structure in the plume. Our results support the subsurface liquid model, with gas escaping and being accelerated through nozzle-like channels to the surface, and are consistent with recent particle composition results from the Cassini Cosmic Dust Analyzer.
dc.publisherAmerican Geophysical Union
dc.rightsAuthor/s retain copyright
dc.sourceGeophysical Research Letters
dc.subjectKeywords: Calculated values; Cassini; Cassini cosmic dust analyzer; Column density; Enceladus; Enceladus plume; Extreme ultraviolet spectrum; Gas jet; Gas velocity; Ion neutral mass spectrometers; Line-of-sight; Particle composition; Saturn's moons; South polar reg
dc.titleThe composition and structure of the Enceladus plume
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume38
dc.date.issued2011
local.identifier.absfor020201 - Atomic and Molecular Physics
local.identifier.ariespublicationf2965xPUB1847
local.type.statusPublished Version
local.contributor.affiliationHansen, C J, Planetary Science Institute
local.contributor.affiliationShemansky, Donald E, Space Environment Technologies Inc
local.contributor.affiliationEsposito, Larry W., University of Colorado
local.contributor.affiliationStewart, A I F, University of Colorado
local.contributor.affiliationLewis, Brenton, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationColwell, J E, University of Central Florida
local.contributor.affiliationHendrix, A R, University of Central Florida
local.contributor.affiliationWest, Robert A, California Institute of Technology Jet Propulsion Laboratory
local.contributor.affiliationWaite, J H, Southwest Research Institute
local.contributor.affiliationTeolis, B, Southwest Research Institute
local.contributor.affiliationMagee, B A, Southwest Research Institute
local.bibliographicCitation.issue11
local.bibliographicCitation.startpage5
local.identifier.doi10.1029/2011GL047415
local.identifier.absseo970102 - Expanding Knowledge in the Physical Sciences
dc.date.updated2016-02-24T08:18:33Z
local.identifier.scopusID2-s2.0-79958840952
local.identifier.thomsonID000291541500002
dcterms.accessRightsOpen Access
CollectionsANU Research Publications

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