The collapse of Io's primary atmosphere in Jupiter eclipse
The collapse of Io's primary atmosphere in Jupiter eclipse
复制标题
木星食中木卫一主要大气层的崩溃
DOI：
10.1002/2016je005025
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
M. Richter
中科院分区：
文献类型：
--
作者：
C. Tsang;J. Spencer;E. Lellouch;M. López‐Valverde;M. Richter
潮汐加热引起的火山放气是木星卫星木卫一周围稀薄的二氧化硫大气的最终来源。表面的二氧化硫霜是否在维持木卫一的大气层和持续的火山排气中发挥了作用，以及在多大程度上发挥了作用，这一问题仍然存在争议。人们认为，对于升华支持的大气层来说，主要大气层应该在木星食期间崩溃，因为二氧化硫蒸气压与表面冰的温度密切相关。由于同时需要高光谱和时间灵敏度以及高信噪比，以前无法直接观测日食中的木卫一大气层。在这里，我们首次展示了双子座望远镜在木星日食中木卫一 SO2 大气 19μm 处的高分辨率光谱。最强的大气带深度从日食前的 2.5±(0.08)% 急剧衰减到日食 40 分钟后的 0.18±(0.16)%。进一步的建模表明，日食进入后不久，大气层就塌陷了，这意味着木卫一的大气层具有强烈的升华控制成分。从食前到食中，大气柱密度下降了 5±2 倍。
Volcanic outgassing due to tidal heating is the ultimate source of a tenuous SO2 atmosphere around Jupiter's moon Io. The question of whether SO2 frost on the surface plays a part, and to what degree, in maintaining Io's atmosphere with the constant volcanic outgassing is still debated. It is believed that for a sublimation‐supported atmosphere, the primary atmosphere should collapse during eclipses by Jupiter, as the SO2 vapor pressure is strongly coupled to the temperature of the ice on the surface. No direct observations of Io's atmosphere in eclipse have previously been possible, due to the simultaneous need for high spectral and time sensitivity, as well as a high signal‐to‐noise ratio. Here we present the first ever high‐resolution spectra at 19 µm of Io's SO2 atmosphere in Jupiter eclipse from the Gemini telescope. The strongest atmospheric band depth is seen to dramatically decay from 2.5 ± (0.08)% before the eclipse to 0.18 ± (0.16)% after 40 min in eclipse. Further modeling indicates that the atmosphere has collapsed shortly after eclipse ingress, implying that the atmosphere of Io has a strong sublimation‐controlled component. The atmospheric column density—from pre‐eclipse to in‐eclipse—drops by a factor of 5 ± 2.