総合解析セミナー

総合解析セミナーは基本的に、毎週木曜日の16:30から行われます。
場所は研究所共同館 3階 講義室です。

date Speaker title
5/10 Tue Satoshi Masuda Collaborative researches on solar flares between Nobeyama Radioheliograph and New Chinese Solar Radio Telescope (MUSER)
Abstract : Recently, a new solar radio telescope (MUSER) has been built in China and soon it will start observations regularly. MUSER observes the sun in the different frequencies from Nobeyama Radioheliograph (NoRH). Combining these two telescopes, we can derive full-sun radio images in the wide frequency range from 0.4 GHz to 34 GHz. This is a quite new dataset in the history of solar radio observations in the world. Using this dataset, we would like to study mainly the following topics, 'particle acceleration process in solar flares' and 'Quasi-periodic pulsation bserved during a solar flare'. The operation of NoRH will be finished at the end of March in 2020, so the two years from now is very important to realize simultaneous observation between MUSER and NoRH.
4/26 Tue Mariko Teramoto Periodic modulations of energetic electron flux and the spatial distributions of Pc5 pulsations observed by the ERG satellite.
Abstract : One widely accepted scenario for the dynamic process of the radiation belt is that ULF oscillations in the Pc5 frequency band drive radial transport. When the electron drift period matches the wave period ULF waves cause violation of the third adiabatic invariant with the first and second invariants conserved. In previous studies, Radiation Belt Storm Probes (RBSP) observations show the evidence for drift-resonant interaction between energetic electron and ULF waves in the inner magnetosphere [Claudepierre et al., 2013, Hao et al.,2014 ].However, spatial variations of energetic electrons affected by ULF waves via drift resonance in the inner magnetosphere have not been reported. To understand spatial properties of energetic electron flux modulations, we compared energetic electron flux modulations observed by RBSP and Exploration of energization and Radiation in Geospace (ERG) satellites separated in longitude. In this presentation, we show that the energetic electron flux modulations over an energy range from 500keV to 2.5 MeV were simultaneously observed in the dawn and dusk sectors by the ERG and RBSP, respectively. While the RBSP satellite observed compressional Pc5 pulsations with the small amplitude in the magnetic field data, no Pc5 pulsations appeared in the magnetic field data obtained by the ERG satellite. We concluded that energetic electron flux were modulated by Pc5 pulsations, which was localized in the noon-dusk sector, via drift-resonance interaction. In this present, we will also present the spatial distributions of Pc5 pulsations observed by the ERG satellite from March 2017 to March 2018.
4/17 Tue Shinnosuke Ishikawa Investigations of high energy plasma in the Sun by high sensitivity X-ray imaging and spectroscopic observations
Abstract : X-ray observations of the Sun is a unique and important tool to investigate energy release processes by detecting high energy plasma including super hot (>10 MK) plasma and accelerated non-thermal particles. The Yohkoh satellite successfully performed X-ray observations of the Sun and contributed to understanding of physical processes of solar flares. For further investigations of the energy release processes in the Sun, high sensitivity imaging and spectroscopic observations are desired to investigate detailed physical processes of energy releases and detect smaller events to evaluate contributions to heating of the corona. However, we had two technical difficulties; sensitivity in hard X-rays, and capability of imaging and spectroscopic observations in soft X-ray range. The sensitivity limitation was caused by an “indirect” imaging technique of past and current instruments, such as modulation collimators. To overcome this difficulty, we performed a sounding rocket experiment Focusing Optics Solar X-ray Imager (FOXSI). FOXSI provides the first focusing observations in hard X-ray energy range, and achieves superior sensitivity to detect faint sources. We performed two successful launches and found tiny energy releases which were not detectable before FOXSI. We also work on soft X-ray imaging spectroscopy of the Sun with high-speed CMOS sensors. Sun was too bright in soft X-rays and time scales of energy release events are too short, it was difficult to perform imaging and spectroscopic observations of the Sun with CCD cameras used in past and current instruments. We will achieve the first photon counting imaging spectroscopy of the Sun by the next launch of the FOXSI sounding rocket experiment this summer. Based on those technologies, we have proposed a satellite mission Physics of Energetic and Non-thermal plasmas in X-region (PhoENiX) to perform high sensitivity soft and hard X-ray imaging and spectroscopic observations. The PhoENiX proposal is now under review for the JAXA satellite to be launched in mid 2020s.
2017年度のセミナー