春分点后的天王星极光
Uranus' aurorae past equinox
摘要：
最近，哈勃太空望远镜（HST）在远紫外线中探测到了天王星的极光，这为从地球上远程研究不对称的天王星磁层提供了一种新的、迄今为止独一无二的手段。我们在这里分析两个新的HST天王星运动在9月执行。2012年和2014年11月，不同的时间范围和变化的太阳风条件下的数值预测的三个不同的MHD代码。总的来说，用太空望远镜成像光谱仪拍摄的HST图像显示了三对连续图像的极光发射（一对在2012年获得，两对在2014年获得），因此总共有六个额外的极光探测，包括HST所见过的最强烈的天王星极光。检测到的排放发生接近预期的行星际冲击的到来。它们在南半球的纬度上看起来像是延伸的斑点，随着地球旋转。它们从H $_2$发出5-24 kR和1.3-8.8 GW的紫外辐射，持续数十分钟，并在几秒的时间尺度上变化。用模型极光椭圆拟合2014年的观测结果，将南（北）磁极的经度限制在天王星经度系统中的104+\-26°（284-\-26°）。我们认为，天王星近分点极光是脉冲尖点发射可能引发的大规模磁层压缩。
英文摘要：
The aurorae of Uranus were recently detected in the far ultraviolet with the Hubble Space Telescope (HST) providing a new, so far unique, means to remotely study the asymmetric Uranian magnetosphere from Earth. We analyze here two new HST Uranus campaigns executed in Sept. 2012 and Nov. 2014 with different temporal coverage and under variable solar wind conditions numerically predicted by three different MHD codes. Overall, HST images taken with the Space Telescope Imaging Spectrograph reveal auroral emissions in three pairs of successive images (one pair acquired in 2012 and two in 2014), hence six additional auroral detections in total, including the most intense Uranian aurorae ever seen with HST. The detected emissions occur close the expected arrival of interplanetary shocks. They appear as extended spots at southern latitudes, rotating with the planet. They radiate 5-24 kR and 1.3-8.8 GW of ultraviolet emission from H$_2$, last for tens of minutes and vary on timescales down to a few seconds. Fitting the 2014 observations with model auroral ovals constrains the longitude of the southern (northern) magnetic pole to 104+\-26° (284-\-26°) in the Uranian Longitude System. We suggest that the Uranian near-equinoctial aurorae are pulsed cusp emissions possibly triggered by large-scale magnetospheric compressions.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
