2023 Fiscal Year Final Research Report

High Precision Polarimetric Observation by a Balloon-Borne Solar Telescope: Revealing Conversion Processes of Magnetic Energy in the Stellar Atmosphere

Research Project

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Project/Area Number	18H05234
Research Category	Grant-in-Aid for Scientific Research (S)
Allocation Type	Single-year Grants
Review Section	Broad Section B
Research Institution	National Astronomical Observatory of Japan
Principal Investigator	Katsukawa Yukio 国立天文台, 太陽観測科学プロジェクト, 教授 (00399289)
Co-Investigator(Kenkyū-buntansha)	清水敏文国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 教授 (60311180) 久保雅仁国立天文台, SOLAR-Cプロジェクト, 助教 (80425777)
Project Period (FY)	2018-06-11 – 2023-03-31
Keywords	宇宙・天体プラズマ / 太陽物理学 / 光赤外線天文学 / 偏光観測 / 気球観測 / 数値モデリング
Outline of Final Research Achievements	We have successfully developed a near-infrared spectro-polarimeter, SCIP, to be mounted on the SUNRISE balloon-borne solar telescope to realize high-resolution and -precision polarization measurements. Through the development, we obtained a mirror scanning mechanism, waveplate rotating mechanism, high-precision polarization measurement technique, and opto-mechanical technique that can be applied to a spacecraft instrument, and published peer-reviewed papers. In numerical modeling research, we developed a method to derive the 3D magnetic fields of the solar atmosphere from spectro-polarimetric data and proposed a method to investigate the driving mechanism of jets and small-scale reconnection, which are key processes in magnetic energy conversion. The SUNRISE balloon was flown in 2022, but the data was not obtained due to a malfunction of the US's gondola. The instruments aboard SUNRISE were recovered in good condition, and preparations are steadily underway for the reflight in 2024.
Free Research Field	宇宙物理学
Academic Significance and Societal Importance of the Research Achievements	高精度偏光観測によって太陽大気の3次元的な磁場構造を描き出すことができ、さらにその空間分布と時間変化から太陽大気の加熱とプラズマ流の駆動を定量化する有用な情報がもたらされることを示した。観測手法を応用して太陽フレア発生領域や太陽風流源の3次元磁場構造の観測を高精度化できれば、惑星環境に影響を及ぼす宇宙天気現象の予測に発展させることができる。本課題を起点として、天体プラズマや実験室プラズマの乱流現象の研究への展開も開始できた。気球望遠鏡搭載装置の開発によって、宇宙望遠鏡用の焦点面観測装置に必要不可欠な技術を獲得でき、今後、日本のグループが国際的な大型宇宙望遠鏡計画に参画する基盤構築に貢献した。