DOI: 10.1029/2018JA025243
Scopus记录号: 2-s2.0-85047637023
论文题名: Hubble Space Telescope Observations of Variations in Ganymede's Oxygen Atmosphere and Aurora
作者: Molyneux P.M. ; Nichols J.D. ; Bannister N.P. ; Bunce E.J. ; Clarke J.T. ; Cowley S.W.H. ; Gérard J.-C. ; Grodent D. ; Milan S.E. ; Paty C.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 5 起始页码: 3777
结束页码: 3793
语种: 英语
英文摘要: We present high-sensitivity Hubble Space Telescope (HST) Cosmic Origins Spectrograph and HST Space Telescope Imaging Spectrograph measurements of atmospheric OI 130.4-nm and OI] 135.6-nm emissions at Ganymede, which exhibit significant spatial and temporal variability. These observations represent the first observations of Ganymede using HST Cosmic Origins Spectrograph and of both the leading and trailing hemispheres within a single HST campaign, minimizing the potential influence of long-term changes in the Jovian plasma sheet or in Ganymede's atmosphere on the comparison of the two hemispheres. The mean disk-averaged OI] 135.6-nm/OI 130.4-nm observed intensity ratio was 2.72 ± 0.57 on the leading hemisphere and 1.42 ± 0.16 on the trailing hemisphere. The observed leading hemisphere ratios are consistent with an O2 atmosphere, but we show that an atomic oxygen component of ~10% is required to produce the observed trailing hemisphere ratios. The excess 130.4-nm emission on the trailing hemisphere relative to that expected for an O2 atmosphere was ~11 R. The O column density required to produce this excess is determined based on previous estimates of the electron density and temperature at Ganymede and exceeds the limit for an optically thin atmosphere. The implication that the O atmosphere is optically thick may be investigated in future by observing Ganymede as it moves into eclipse or by determining the ratio of the individual components within the 130.4-nm triplet. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/113930
Appears in Collections: 气候减缓与适应
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作者单位: Southwest Research Institute, San Antonio, TX, United States; Department of Physics and Astronomy, University of Leicester, Leicester, United Kingdom; Center for Space Physics, Boston University, Boston, MA, United States; Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium; School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, United States
Recommended Citation:
Molyneux P.M.,Nichols J.D.,Bannister N.P.,et al. Hubble Space Telescope Observations of Variations in Ganymede's Oxygen Atmosphere and Aurora[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(5)