Origin of Saturn's aurora: Simultaneous observations by Cassini and the Hubble Space Telescope
Origin of Saturn's aurora: Simultaneous observations by Cassini and the Hubble Space Telescope
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DOI：
10.1029/2008ja013257
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发表时间：
2008-09
期刊：
影响因子：
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通讯作者：
E. Bunce;C. Arridge;J. Clarke;A. Coates;S. Cowley;M. Dougherty;Jean-Claude Gérard;D. Grodent;K. Hansen;J. Nichols;D. Southwood;D. Southwood;D. Talboys
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文献类型：
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作者：
E. Bunce;C. Arridge;J. Clarke;A. Coates;S. Cowley;M. Dougherty;Jean-Claude Gérard;D. Grodent;K. Hansen;J. Nichols;D. Southwood;D. Southwood;D. Talboys
外行星极光的成像已经有十多年了，但了解它们的物理起源需要同时进行远程和现场观测。2007年1月，哈勃太空望远镜拍摄到了土星的紫外线极光，卡西尼号飞船在正午时分越过了与高纬度磁层极光椭圆相连的磁场线。卡西尼号的数据表明，正午的极光位于开场线和闭场线之间的边界，在那里有一层向上定向的场对准电流，其密度要求磁层电子向下加速，足以产生极光。这些观测结果表明，准连续的主椭圆是由磁层-太阳风相互作用通过开闭场线边界上的旋转流切变产生的。
Outer planet auroras have been imaged for more than a decade, yet understanding their physical origin requires simultaneous remote and in situ observations. The first such measurements at Saturn were obtained in January 2007, when the Hubble Space Telescope imaged the ultraviolet aurora, while the Cassini spacecraft crossed field lines connected to the auroral oval in the high-latitude magnetosphere near noon. The Cassini data indicate that the noon aurora lies in the boundary between open- and closed-field lines, where a layer of upward-directed field-aligned current flows whose density requires downward acceleration of magnetospheric electrons sufficient to produce the aurora. These observations indicate that the quasi-continuous main oval is produced by the magnetosphere-solar wind interaction through the shear in rotational flow across the open-closed-field line boundary.