Local-time averaged maps of H3+ emission, temperature and ion winds.
Local-time averaged maps of H3+ emission, temperature and ion winds.
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H3 排放、温度和离子风的本地时间平均图。
DOI：
10.1098/rsta.2018.0405
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Stallard TS
中科院分区：
文献类型：
--
作者：
Stallard TS
我们提出了一个月内采取的土星'saurora的Rank-NIRSPEC观测，以支持卡西尼使命的'大结局'。这些观测首次产生了土星温度和离子风的二维地图。这些地图显示出令人惊讶的复杂性，每晚都有不同的形态。离子风揭示了在主要极光发射中的多个0.5-1 km s-1的离子流弧。虽然这些流动弧每晚发生在不同的位置，但它们显示出复杂的结构，包括地球黎明和黄昏时的镜像流动。这些流动与由太阳风或外磁层驱动的轴对称电流模型或与土星可变旋转速率相关的行星周期电流模型预测的流动不匹配。所有夜晚离子风的平均值显示，黎明一侧有一个狭窄且集中的约0.3 km s-1气流，而黄昏一侧则有一个更宽且更广泛的1-2 km s-1亚共转，分裂成多个弧形。温度图显示了电离层温度的急剧梯度，整个极光区在300至600 K之间变化。这些温度变化是局部的，导致极光区的热点和冷点。这些在几个晚上似乎有点稳定，但在更长的时间内会发生显着变化。这些温度极值的位置并没有很好地由行星周期组织起来，也没有证据表明行星周期电流系统的热层驱动因素。由于没有过去的磁层或热层模型解释这里观察到的丰富的复杂性，这些测量代表了一个奇妙的新资源，揭示了土星的热层，电离层和磁层之间的相互作用的复杂性。这篇文章是讨论会议问题的一部分“氢分子离子的进展：H3+，H5+和超越”。
We present Keck-NIRSPEC observations of Saturn'saurora taken over a period of a month, in support of the Cassini mission's ‘Grand Finale’. These observations produce two-dimensional maps of Saturn'stemperature and ion winds for the first time. These maps show surprising complexity, with different morphologies seen in each night. Theion winds reveal multiple arcs of 0.5–1 km s−1ion flows inside the main auroral emission. Although these arcs of flow occur in different locations each night, they show intricate structures, including mirrored flows on the dawn and dusk of the planet. These flows do not match with the predicted flows from models of either axisymmetric currents driven by the Solar Wind or outer magnetosphere, or the planetary periodic currents associated with Saturn's variable rotation rate. The average of the ion wind flows across all the nights reveals a single narrow and focused approximately 0.3 km s−1flow on the dawn side and broader and more extensive 1–2 km s−1sub-corotation, spilt into multiple arcs, on the dusk side. The temperature maps reveal sharp gradients in ionospheric temperatures, varying between 300 and 600 K across the auroral region. These temperature changes are localized, resulting in hot and cold spots across the auroral region. These appear to be somewhat stable over several nights, but change significantly over longer periods. The position of these temperature extremes is not well organized by the planetary period and there is no evidence for a thermospheric driver of the planetary period current system. Since no past magnetospheric or thermospheric models explain the rich complexity observed here, these measurements represent a fantastic new resource, revealing the complexity of the interaction between Saturn's thermosphere, ionosphere and magnetosphere.This article is part of a discussion meeting issue ‘Advances in hydrogen molecular ions: H3+, H5+and beyond’.