solar-flare researches based on the multi-wavelength simultaneous imaging obsevations of solar radio telescopes in Japan and China

2022 Fiscal Year Final Research Report

• Project/Area Number: 18H01253
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: Nagoya University
• Principal Investigator: Masuda Satoshi 名古屋大学, 宇宙地球環境研究所, 准教授 (10262916)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 太陽フレア / 粒子加速 / 電波

Outline of Final Research Achievements

We promoted international joint research on particle acceleration phenomena of solar flares with the group of the new solar radio telescope ‘MUSER’ in China. We performed a detailed analysis of events simultaneously observed with the Nobeyama Radioheliograph (NoRH), which finished its scientific operation in March 2020, and MUSER, which was in the test observation phase. MUSER captured particle acceleration signatures above the magnetic reconnection site of a solar flare, and NoRH simultaneously observed a brightening corresponding to the acceleration below the magnetic reconnection site. These observational facts suggest that particle acceleration simultaneously takes place above and below the reconnection site. In addition, the temporal behavior in the frequency-drift characteristics of a lot of tiny radio bursts observed with MUSER indicates that the particle acceleration region was moving upward at high speed.

Free Research Field

太陽物理学

Academic Significance and Societal Importance of the Research Achievements

まず、太陽フレアの標準モデルである磁気リコネクションによるエネルギー解放モデルを想定した場合、そのエネルギー解放領域の上空と下方で同時に粒子加速が起きていることを示す重要な観測結果が得られた。フレア領域が、太陽から惑星間空間につながる磁場を含んでいた場合、高エネルギー粒子が惑星間空間に流出すると考えられ、宇宙天気研究にもつながる。また、本研究では上空の粒子加速領域が高速で上方に移動している可能性を示唆する結果を得た。これは、上空に放出されたプラズモイド周辺での粒子加速だと解釈でき、プラズマ物理学の理論計算や室内実験で説明・実証すべき課題を提起することになる。