From the Sun to the Stars: Building of a Universal Theory of Spots and Flares Based on Numerical and Observational Studies

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K17671
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Astronomy
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Toriumi Shin 国立天文台, 太陽天体プラズマ研究部, 特任助教 (30738290)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 太陽物理学 / プラズマ物理学 / 磁気流体力学 / 太陽黒点 / 太陽フレア

Outline of Final Research Achievements

It is known that the flares on the Sun and stars, which are the releasing of magnetic energy, tend to appear in active regions (ARs) including sunspots. With the aim to reveal the mechanisms behind these phenomena, we performed the following research activities. (1) Analyzing the observational data of strong solar flares for six years, we revealed the relationship between the flare durations and AR magnetic fields, and the magnetic structures of flare-productive ARs. (2) We numerically reproduced the magnetic structures of flaring ARs and elucidated the importance of twist and interaction of magnetic fields within the stellar interior. (3) With thermo-dynamical simulations, we unraveled the statistical relation between the flare durations and AR magnetic fields and discussed the possible application to the stellar flare data. (4) Related studies were also performed.

Free Research Field

太陽物理学

Academic Significance and Societal Importance of the Research Achievements

本研究課題によって、大型の太陽フレアを生じやすい黒点の磁場構造や、その形成過程が明らかになった。また、太陽フレアの継続時間と磁場構造との相関関係を明らかにしたことで、空間分解観測の不可能な恒星フレアについても、フレア継続時間を測定することで磁場構造を解明できる可能性が示された。恒星黒点・恒星フレアの研究者との議論を通じ、実際の観測データにこれらの理論を応用する道筋をつけることができた。また、これらの諸現象を観測的・理論的観点からまとめた総説論文を執筆し、成果を広くコミュニティに還元できた。