Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM07] Space Weather, Space Climate, and VarSITI

Mon. May 25, 2015 2:15 PM - 4:00 PM 302 (3F)

Convener:*Ryuho Kataoka(National Institute of Polar Research), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University), Toshifumi Shimizu(Institute of Space and Astronautical Science, JAXA), Ayumi Asai(Unit for Synergetic Studies of Space, Kyoto University), Hidekatsu Jin(National Institude of Information and Communications Technology), Tatsuhiko Sato(Japan Atomic Energy Agency), Kanya Kusano(Solar-Terrestrial Environment Laboratory, Nagoya University), Hiroko Miyahara(College of Art and Design, Musashino Art University), Takuji Nakamura(National Institute of Polar Research), Kazuo Shiokawa(Solar-Terrestrial Environment Laboratory, Nagoya University), Kiminori Itoh(Graduate School of Engineering, Yokohama National University), Chair:Ryuho Kataoka(National Institute of Polar Research)

3:00 PM - 3:15 PM

[PEM07-22] Characteristics that enhance white-light emission in solar flares

*Kyoko WATANABE1, Satoshi MASUDA2, Jun KITAGAWA2 (1.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 2.Solar-Terrestrial Environment Laboratory, Nagoya University)

Keywords:solar flare, white-light, particle acceleration

In association with large (such as X-class) solar flares, we sometimes observe enhancements of visible continuum radiation, which is known as a "white-light flare". Because many white-light events show a close correlation between the time profiles and locations of white-light emission, and the hard X-rays and/or radio emission, it is believed that the origin of white-light emission is non-thermal electrons. However, not all large solar flares have white-light enhancements, and non-thermal electrons exist even in micro-flares. There should be some necessary condition to generate white-light enhancements.
To understand what conditions generate a white-light flare, we analyzed 42 M- and X-class flares observed with Hinode/SOT during the period from January 2011 to August 2013. Comparing the white-light (19 events) and no white-light (23 events) events, we concluded that the key factor needed to generate white-light enhancement is the precipitation of large amounts of nonthermal electrons into a compact region within a short time duration (Kitagawa et al., submitted to ApJ).
In this paper, we present the statistical results until December 2014. Not only the Hinode/SOT white-light (G-band (4305A) and continuum (Blue: 4505A, Green: 5550A, Red: 6684A)) data, but we also check SDO/HMI continuum data. The total number of events is now about twice that of Kitagawa's study. We compared the white-light emission data with GOES, hard X-ray emission data and/or the strength of the photospheric magnetic fields and looked for any relationship between them.