Jupiter's X‐ray and EUV auroras monitored by Chandra, XMM‐Newton, and Hisaki satellite

Abstract

Jupiter's X‐ray auroral emission in the polar cap region results from particles which have undergone strong field‐aligned acceleration into the ionosphere. The origin of precipitating ions and electrons and the time variability in the X‐ray emission are essential to uncover the driving mechanism for the high‐energy acceleration. The magnetospheric location of the source field line where the X‐ray is generated is likely affected by the solar wind variability. However, these essential characteristics are still unknown because the long‐term monitoring of the X‐rays and contemporaneous solar wind variability has not been carried out. In April 2014, the first long‐term multiwavelength monitoring of Jupiter's X‐ray and EUV auroral emissions was made by the Chandra X‐ray Observatory, XMM‐Newton, and Hisaki satellite. We find that the X‐ray count rates are positively correlated with the solar wind velocity and insignificantly with the dynamic pressure. Based on the magnetic field mapping model, a half of the X‐ray auroral region was found to be open to the interplanetary space. The other half of the X‐ray auroral source region is magnetically connected with the prenoon to postdusk sector in the outermost region of the magnetosphere, where the Kelvin‐Helmholtz (KH) instability, magnetopause reconnection, and quasiperiodic particle injection potentially take place. We speculate that the high‐energy auroral acceleration is associated with the KH instability and/or magnetopause reconnection. This association is expected to also occur in many other space plasma environments such as Saturn and other magnetized rotators.

Response of Jupiter's Aurora to Plasma Mass Loading Rate Monitored by the Hisaki Satellite During Volcanic Eruptions at Io

“…Uncertainty in the arrival time of the solar wind shock structures, the Corotating Interaction Region and Coronal Mass Ejections, at Jupiter is dependent on the Earth‐Sun‐Jupiter angle, which was 82°–180° for the present analysis period. The arrival time uncertainty is estimated to be approximately a few days or more, as discussed in Kimura et al (, ), Kita et al (), and Tao et al (, ).…”

Response of Jupiter's inner magnetosphere to the solar wind derived from extreme ultraviolet monitoring of the Io plasma torus

“…The whole shape of the slit is dumbbell like so that emissions from the Jupiter's aurora can be detected simultaneously. The northern polar region of Jupiter was set to the center of the slit to measure Jupiter's northern aurora in this observation period [ Kimura et al ., , ; Tao et al ., ; Badman et al ., ]; however, the aurora part is out of the scope of this paper. For the IPT part, the spectral resolution is ~0.6 nm and the spatial resolution is ~17 arcsec (corresponding to ~0.7 R J in the horizontal direction).…”

Response of Jupiter's auroras to conditions in the interplanetary medium as measured by the Hubble Space Telescope and Juno

“…The dynamics of Jupiter's magnetosphere are dominated by planetary rotation and the outflow of material from Io [see, e.g., Khurana et al, 2004;Clarke et al, 2004], and the nature of the solar wind interaction has long been debated [Brice and Ioannidis, 1970;Southwood and Kivelson, 2001;Nichols et al, 2006;Badman and Cowley, 2007;McComas and Bagenal, 2007;Cowley et al, 2008;Delamere and Bagenal, 2010]. Observationally, Geophysical Research Letters 10.1002/2017GL073029 the total power of the Jovian auroras in various wavelengths exhibits modulation by interplanetary conditions [Baron et al, 1996;Pryor et al, 2005;Clarke et al, 2009;Badman et al, 2016;Kita et al, 2016;Kimura et al, 2016;Dunn et al, 2016], particularly increasing in some cases (not all) in response to expected solar wind compression regions characterized by overall high dynamic pressure and interplanetary magnetic field (IMF) strength.…”