Io plasma torus and Jovian aurora activity during the Juno era: Current status of Hisaki/EXCEED
Abstract
Hisaki is an earth orbiting extreme ultraviolet spectroscope (EXCEED) which was launched on 14 September 2013. Hisaki has carried out unprecedented continuous observation of Io plasma torus and Jovian aurora and found responses of the Jovian magnetosphere to volcanic activities of Io and the solar wind. In the spring of 2015, Hisaki observed a major volcanic enhancement of Io. The first simultaneous observation of oxygen neutral cloud around Io and plasma torus enabled us to examine life cycle of oxygen from production at Io to loss by outward transport (Koga et al. 2019). From detailed spectral analysis, we found unexpected hot electron population in dusk side of Io plasma torus, suggesting that the mass increase in the torus with volcanic activity enhanced the plasma transport from the outside within a specific region or via a local heating process (Hikida et al. 2019). Modeling attempts to explain unresolved delayed corotation of Io plasma torus observed by Hisaki (Tsuchiya et al. 2019) has been done in the light of magnetosphere ionosphere coupling (Coffin et al. 2020).
Since the autumn of 2016, the Juno spacecraft was in the orbit around Jupiter. Before the arrival of Jupiter, Juno monitored the solar wind upstream from Jupiter and the solar wind variations were compared with ultraviolet aurora variations to find detailed time response of the aurora to the solar wind (Kita et al. 2019). Juno reveled not only aurora particle accelerations but structure and dynamics of magnetic field and plasma in the magnetosphere. Hisaki monitored activities of the magnetosphere and Io's volcanoes from the aurora and Io plasma observations (Yao et al. 2019, Roth et al. 2020). While major volcanic activities such like that occurred in 2015 have not be found in the Juno mission period yet, Hisaki see moderate changes in Io plasma torus, which could be caused by the volcanic activity. Hisaki also see aurora brightening which may be caused by internal magnetospheric process and/or the solar wind. These datasets will provide unique opportunities to compare detailed in-situ observation by Juno with global view of the magnetosphere by Hisaki. JAXA approved extension of Hisaki mission period by the end of March 2022. During the extended mission period, Hisaki will continue long-term monitoring of Io plasma torus and other solar system planets such as Mars.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMSM0560004T
- Keywords:
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- 2704 Auroral phenomena;
- MAGNETOSPHERIC PHYSICS;
- 2756 Planetary magnetospheres;
- MAGNETOSPHERIC PHYSICS;
- 5719 Interactions with particles and fields;
- PLANETARY SCIENCES: FLUID PLANETS;
- 6220 Jupiter;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS