Title：Polar magnetospheric activities of Jupiter and its inner radiation belt

Reporter：Prof. Yu-Qing Lou

Tsinghua University

Time：Mar. 9th (Thursday) 3:00pm-5:00pm

Place：B-515, Lee Shau Kee Building of Science and Technology

Abstract：In 1992, Ulysses spacecraft discovered quasi-periodic 40 minute (QP-40) bursts of relativistic electrons and of associated low-frequency radio emissions from the south polar direction of Jupiter. These radio bursts are right-hand circularly polarized and strongly correlate with arrivals of fast-speed solar winds at Jupiter. We proposed (Lou 2001) that these relativistic electron bursts originate from the circumpolar leakage of Jupiter's inner radiation belt (IRB) where intense synchrotron emissions reveal the presence of trapped relativistic electrons therein and based on this, we predicted that such QP-40 activities should be global as confirmed by later observations. In particular, such QP-40 radio bursts from the north polar direction should be left-hand circularly polarized and also strongly correlate with arrivals of fast-speed solar winds at Jupiter. Inside the Jovian magnetosphere, one should also detect associated QP-40 bursts of relativistic electrons from the north polar region. In our scenario, the QP-40 variabilities are associated with QP-40 magneto-inertial global IRB oscillations (Lou 2001) which are excited and sustained by intermittent high-speed solar winds (Lou 1994, 1996). Around the end of 2000 during the joint campaign of Cassini fly-by, HST and Chandra, the high-resolution camera (HRC) of Chandra X-ray Observatory discovered QP-45 variability of X-ray hot spot within north aurora oval of Jupiter during 10 hour observation (Gladstone et al. 2002). Using the real-time solar wind data from the spacecraft Advanced Composition Explorer (ACE), our subsequent analysis indicates a likely coincidence of X-ray hot spot QP-45 variability with the arrival of high-speed solar wind at Jupiter (Lou & Zheng 2003). After monitoring of several years, we published 150px observations of Jupiter's IRB flux variations using the Urumqi 25m radio telescope in Xin Jiang Province of China（Lou et al. 2012）. In reference to extensive observations of different diagnostics and the ongoing JUNO mission, we discuss various aspects of our model scenario and predictions more specifically. The prospect of joint space (X-ray, EUV) and ground (radio and optical) observational campaigns to monitor global magnetic activities of Jupiter are also discussed.

References

1. Y.-Q. Lou, The Astrophysical Journal, 548, 460 (2001).

2. Y.-Q. Lou, and C. Zheng, Mon. Not. Roy. Astron. Soc. Letters, 344, L1 (2003).

3. Y.-Q. Lou, H.G. Song, Y.Y. Liu, and M. Yang, Mon. Not. Roy. Astron. Soc.

Letters, 421, L62 (2012).

4. Y.-Q. Lou, Geophysical Research Letters, 23, 609 (1996).

5. Y.-Q. Lou, Journal of Geophysical Research, 99, 14747 (1994).

6. G.R. Gladstone, et al., Nature, 415, 1000 (2002).

Brief Biography：

National Examination 1977, Northern Jiao Tong University,

Winner of 1981 CUSPEA Program sponsored by Professor T.D. Lee,

PhD in Physics 1987 Harvard University,

Yangtze Professor 2002 in Physics, Tsinghua University