The impact of an ICME on the Jovian X-ray aurora.

We report the first Jupiter X‐ray observations planned to coincide with an interplanetary coronal mass ejection (ICME). At the predicted ICME arrival time, we observed a factor of ∼8 enhancement in Jupiter's X‐ray aurora. Within 1.5 h of this enhancement, intense bursts of non‐Io decametric radio emission occurred. Spatial, spectral, and temporal characteristics also varied between ICME arrival and another X‐ray observation two days later. Gladstone et al. (2002) discovered the polar X‐ray hot spot and found it pulsed with 45 min quasiperiodicity. During the ICME arrival, the hot spot expanded and exhibited two periods: 26 min periodicity from sulfur ions and 12 min periodicity from a mixture of carbon/sulfur and oxygen ions. After the ICME, the dominant period became 42 min. By comparing Vogt et al. (2011) Jovian mapping models with spectral analysis, we found that during ICME arrival at least two distinct ion populations, from Jupiter's dayside, produced the X‐ray aurora. Auroras mapping to magnetospheric field lines between 50 and 70 R J were dominated by emission from precipitating sulfur ions (S7+,…,14+). Emissions mapping to closed field lines between 70 and 120 R J and to open field lines were generated by a mixture of precipitating oxygen (O7+,8+) and sulfur/carbon ions, possibly implying some solar wind precipitation. We suggest that the best explanation for the X‐ray hot spot is pulsed dayside reconnection perturbing magnetospheric downward currents, as proposed by Bunce et al. (2004). The auroral enhancement has different spectral, spatial, and temporal characteristics to the hot spot. By analyzing these characteristics and coincident radio emissions, we propose that the enhancement is driven directly by the ICME through Jovian magnetosphere compression and/or a large‐scale dayside reconnection event. The arrival of an ICME changes Jupiter's X‐ray auroral spectra, spatial, and temporal characteristics Jupiter's X‐ray aurora maps to sources in the outer magnetosphere and also to open field lines Jupiter's X‐ray aurora is produced by two distinct ion populations during the ICME

我们报道了首次计划与行星际日冕物质抛射（ICME）同时进行的木星X射线观测。在预测的ICME到达时间，我们观测到木星X射线极光增强了约8倍。在这次增强的1.5小时内，出现了强烈的非木卫一十米波射电爆发。在ICME到达时和两天后的另一次X射线观测之间，空间、光谱和时间特性也有所不同。格拉德斯通等人（2002年）发现了极地X射线热点，并发现它以45分钟的准周期性脉动。在ICME到达期间，热点扩大并呈现出两个周期：硫离子的26分钟周期以及碳/硫和氧离子混合的12分钟周期。在ICME之后，主导周期变为42分钟。通过将沃格特等人（2011年）的木星映射模型与光谱分析进行比较，我们发现在ICME到达期间，至少有两个来自木星昼侧的不同离子群产生了X射线极光。映射到50至70RJ之间磁层场线的极光主要由沉降硫离子（S7 +，…，14 +）的发射所主导。映射到70至120RJ之间闭合场线以及开放场线的发射是由沉降氧（O7 +，8 +）和硫/碳离子的混合物产生的，这可能意味着一些太阳风沉降。我们认为，对X射线热点的最佳解释是如邦斯等人（2004年）所提出的，昼侧的脉冲重联扰动了磁层向下的电流。极光增强与热点具有不同的光谱、空间和时间特性。通过分析这些特性以及同时发生的射电发射，我们提出增强是由ICME通过木星磁层压缩和/或大规模昼侧重联事件直接驱动的。 ICME的到达改变了木星X射线极光的光谱、空间和时间特性 木星的X射线极光映射到外磁层的源以及开放场线 在ICME期间，木星的X射线极光是由两个不同的离子群产生的