The domination of Saturn’s low-latitude ionosphere by ring ‘rain’
The domination of Saturn’s low-latitude ionosphere by ring ‘rain’
复制标题
环“雨”对土星低纬度电离层的支配
作者：
J. O’Donoghue;T. Stallard;H. Melin;G. Jones;S. Cowley;S. Miller;K. Baines;J. Blake
土星的电离层是在中性大气暴露于高能带电粒子流或太阳辐射时产生的。在低纬度地区，太阳辐射会导致微弱的行星范围内的红外光，这与太阳对行星的均匀照射相对应。然而，观测到的低纬度电离层的电子密度比模型预测的要低，电离层的温度要高。此前曾有人提出行星与土星环之间存在磁连接，从土星环流入的水可以解释土星大气中低于预期的电子密度。在这里，我们报告了探测到的一种特征模式，它横跨从25度到60度的宽纬度带，叠加在低纬度的背景光上，发射的峰值沿着行星的磁力线映射到土星环的间隙。这一模式意味着来自水的带电物质从环面转移到电离层，在全球范围内大量涌入，淹没了土星上层大气表面的30%至43%。这种环“雨”在调制电离层发射和抑制电子密度方面很重要。
Saturn’s ionosphere is produced when the otherwise neutral atmosphere is exposed to a flow of energetic charged particles or solar radiation. At low latitudes the solar radiation should result in a weak planet-wide glow in the infrared, corresponding to the planet’s uniform illumination by the Sun. The observed electron density of the low-latitude ionosphere, however, is lower and its temperature higher than predicted by models,,. A planet-to-ring magnetic connection has been previously suggested, in which an influx of water from the rings could explain the lower-than-expected electron densities in Saturn’s atmosphere,,. Here we report the detection of a pattern of features, extending across a broad latitude band from 25 to 60 degrees, that is superposed on the lower-latitude background glow, with peaks in emission that map along the planet’s magnetic field lines to gaps in Saturn’s rings. This pattern implies the transfer of charged species derived from water from the ring-plane to the ionosphere, an influx on a global scale, flooding between 30 to 43 per cent of the surface of Saturn’s upper atmosphere. This ring ‘rain’ is important in modulating ionospheric emissions and suppressing electron densities.
来自卡西尼-惠更斯号的土星
DOI：
10.1007/978-1-4020-9217-6_12
发表时间：
2009
期刊：
--
影响因子：
--
作者：
Kurth W
通讯作者：
Kurth W
影响因子：
5.2
作者：
Burton M
通讯作者：
Burton M