SM31C-2504
Jovian Auroral X-ray Emission Coinciding with an Interplanetary Coronal Mass Ejection

Wednesday, 16 December 2015
Poster Hall (Moscone South)
William Dunn1, Graziella Branduardi-Raymont2, Ronald Elsner3, Marissa Vogt4, Laurent Lamy5, Peter G Ford6, Andrew J Coates7, Randy Gladstone8, Caitriona M Jackman9, Jonathan D Nichols10, Jonathan Rae9, Ali Varsani9, Tomoki Kimura11, Kenneth C Hansen12 and Jamie Matthew Jasinski9, (1)Mullard Space Science Laboratory, Dorking, RH5, United Kingdom, (2)University College London, Mullard Space Science Laboratory, London, United Kingdom, (3)NASA Marshall Space Flight Center, Huntsville, AL, United States, (4)Boston University, Boston, MA, United States, (5)Paris Observatory Meudon, LESIA, Meudon, France, (6)MIT, Cambridge, MA, United States, (7)University College London, Centre for Planetary Sciences (at UCL/Birkbeck), London, United Kingdom, (8)Southwest Research Inst, San Antonio, TX, United States, (9)University College London, London, United Kingdom, (10)University of Leicester, Leicester, United Kingdom, (11)RIKEN, Wako, Japan, (12)University of Michigan Ann Arbor, Ann Arbor, MI, United States
Abstract:
The extent of the Solar Wind influence on Jupiter’s X-ray aurora is yet to be understood. To probe this relationship, we compare two Chandra X-ray observations of Jupiter: one coinciding with the predicted arrival of an Interplanetary Coronal Mass Ejection (ICME) and another observation two days later. During the observation coincident with the ICME, we observe a bright auroral enhancement of a factor of 8 in a region normally absent of X-rays. This enhancement occurs ~1 hour before a burst of non-Io Decametric radio emission, believed to be associated with solar wind forward shocks [Hess et al. 2012, 2014]. We also find variation in X-ray auroral periodic behaviour, spatial and spectral distributions.

We use magnetosphere-ionosphere mapping [Vogt et al. 2011] to identify the source of ions generating the X-rays and find that they originate from 10:30-18:00 magnetospheric local time (MLT) in regions of the outer magnetosphere close to the magnetopause. The model also maps some precipitation to open field lines. This suggests that X-rays may provide an excellent tool for analysing the Jovian outer magnetosphere and the processes occurring between the Jovian magnetopause and the solar wind.

As discovered by Gladstone et al. [2002] discovery, we find an X-ray hot spot that pulses with quasi-periodicity. Measurements of this periodicity suggest 2 distinct ion populations generate the Jovian X-ray aurora: a sulphur/carbon dominated population from the middle to outer magnetosphere with a period of 26 minutes, and a combined oxygen and carbon/sulphur population from close to the magnetopause with a period of 12 minutes. The source region and periodicity support findings by Bunce et al. [2004] that pulsed dayside reconnection could energise the outer magnetosphere and drive X-ray emission

To better understand the persistence of these features and/or their relationship to the ICME, we compare these 2011 observations with preliminary analysis of Chandra X-ray observations of Jupiter from 2007. At this time, New Horizons was approaching the planet. We hope that this will provide a useful analogy for the Spring 2016 Juno approach.

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