Japan Geoscience Union Meeting 2016

Presentation information


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

[P-EM19] Heliosphere and Interplanetary Space

Wed. May 25, 2016 10:45 AM - 12:15 PM 302 (3F)

Convener:*Ken Tsubouchi(Tokyo Institute of Technology), Masaki N Nishino(Institute for Space-Earth Environmental Research, Nagoya University), Yasuhiro Nariyuki(Faculty of Human Development, University of Toyama), Chair:Daikou Shiota(Institute for Space and Earth Environmental Research, Nagoya University)

11:30 AM - 11:45 AM

[PEM19-04] Comparison between Polarization and Spectral Characteristics
of Zebra Pattern in Solar Radio Bursts

*Kazutaka Kaneda1, Hiroaki Misawa1, Kazumasa Iwai2, Fuminori Tsuchiya1, Takahiro Obara1 (1.Planetary Plasma and Atmospheric Research Center, Graduated School of Science, Tohoku University, 2.National Institute of Information and Communications Technology)

Keywords:Solar corona, Radio bursts, polarization, AMATERAS

Zebra pattern (ZP) is one of the spectral fine structures superimposed on the broadband type IV continuum, which has a characteristic spectral pattern with a number of parallel drifting stripes. Since these spectral fine structures reflect their emission mechanisms, we can obtain information from their characteristics about physical processes such as particle acceleration, excitation of electrostatic waves and their conversion to electromagnetic waves. Polarization of emission is important to know its emission mechanism. However, the relationship between spectral characteristics of ZP and its polarization has not been understood. In this study, we aim to reveal the generation mechanism of ZP by investigating their polarization characteristics.
In Kaneda et al. (2015, ApJL), we analyzed polarization characteristics of a ZP event and suggested from its frequency dependence that the ZP was originally generated polarized in the O-mode and was partly converted into the X-mode near the emission source. In order to examine these results, we analyzed totally 17 ZP events observed with AMATERAS, a solar radio telescope developed by Tohoku University in the frequency range of 100-500 MHz (Iwai et al., 2012). The analysis was made focused on three aspects: degree of circular polarization, temporal delay between the two polarization components and frequency separation between adjacent stripes. We derived these three parameters using highly resolved spectral data from AMATERAS. As a result, we found the following characteristics; degree of polarization in the range of 10-80%, temporal delay of 0-70 ms and frequency separation of 1-5 MHz, and that these characteristics of ZP were rather different from event to event. The difference in these parameters implies the difference in physical mechanisms at a certain stage of the generation of ZP emission. Based on the obtained results, possible generation mechanisms of ZP will be discussed.