Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS01] Outer Solar System Exploration Today, and Tomorrow

Wed. May 27, 2015 11:00 AM - 11:45 AM A03 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Jun Kimura(Earth-Life Science Institute, Tokyo Institute of Technology), Masaki Fujimoto(Institite of Space and Astronautical Science, Japan Aerospace Exploration Agency), Yasumasa Kasaba(Dep. Geophysics Graduate School of Science Tohoku University), Sho Sasaki(Department of Earth and Space Sciences, School of Science, Osaka University), Takayuki Tanigawa(School of Medicine, University of Occupational and Environmental Health), Yasuhito Sekine(Department of Complexity Science and Enginerring, Graduate School of Frontier Science, University of Tokyo), kunio Sayanagi(Hampton University), Steven Vance(Jet Propulsion Laboratory, Caltech), Chair:Yasumasa Kasaba(東北大学大学院 ), Masaki Fujimoto(Institite of Space and Astronautical Science, Japan Aerospace Exploration Agency)

11:15 AM - 11:30 AM

[PPS01-22] Local electron heating around Io observed by the HISAKI satellite

*Fuminori TSUCHIYA1, Masato KAGITANI1, Kazuo YOSHIOKA2, Hiromasa NOZAWA2, Tomoki KIMURA3, Go MURAKAMI2, Atsushi YAMAZAKI2, Yasumasa KASABA4, Takeshi SAKANOI1, Ichiro YOSHIKAWA5 (1.Planetary Plasma and Atmospheric Research Center, Tohoku Univ., 2.National Institute of Technology, Kagoshima College, 3.ISAS/JAXA, 4.Graduate school of Science, Tohoku University, 5.Department of Complexity Science and Engineering, Univ. of Tokyo)

Keywords:Jovian magnetosphere

Io-correlated brightness change in Io plasma torus (IPT) has been discovered by the Voyager spacecraft and show an evidence of local electron heating around Io. However, the observation data is still limited to investigate its detail properties and cause of the electron heating around Io is still open issue. EUV spectrograph onboard the HISAKI satellite carried out continuous observation of IPT and Jovian aurora for 2.5 months since the end of Dec. 2013. It covers wavelength range from 55 to 145 nm, a wide slit which had a field of view of 400 x 140 arc-second was chosen to measure radial distribution and time variation of IPT. Observation of IPT with HISAKI found clear periodic variation in the IPT brightness associated with Io's orbital period. The Io phase dependence shows that bright region is located just downstream of Io. The amplitude was larger in the short wavelength than in long wavelength. These are evidence of local electron heating around/downstream of Io and consistent with the Voyager result. In addition, it is found that the brightness also depends on the system-III longitude of Jupiter and has local maximum around 120 and 300 degrees. Based on an empirical model of IPT, electron density at Io also shows maxima around the same longitudes. This suggests that the electron heating process is related with IPT density at Io. Total radiated power from IPT on Jan. 2014 was 1.1 TW, which was about a half of the power measured by the Cassini UVIS instrument on Oct. 2000. Io-correlated component has about 10 % of the total radiated power, showing that about 100 GW of power was converted to heat thermal electron in IPT immediately after the generation of source energy around Io.