Study on the driving mechanism of solar magnetic activity with emphasis on magnetic helicity

• Project/Area Number: 15K05034
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Sakurai Takashi 国立天文台, 太陽観測科学プロジェクト, 名誉教授 (40114491)
• Co-Investigator(Renkei-kenkyūsha): HAGINO Masaoki 国立天文台, 太陽観測科学プロジェクト, 専門研究職員 (90437195)
• Research Collaborator: SHINODA Kazuya 国立天文台, 太陽観測科学プロジェクト, 技師 ; MORITA Satoshi 国立天文台, 太陽観測科学プロジェクト, 特任専門員
• Project Period (FY): 2015-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2017: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2015: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
• Keywords: 太陽 / 磁場 / 黒点 / 磁気ヘリシティ / 太陽活動サイクル / ダイナモ機構

Outline of Final Research Achievements

In order to study the driving mechanism of solar magnetic activity, we have developed a new method of deriving the magnetic field on the solar surface from the polarization observation data of spectral lines. In the new method, the magnetic field in a single pixel is assumed to consist of a strong flux-tube field and a weak but non-zero background field (this is an extension of the conventional theory that assumes non-magnetic background). We also considered the origin of helicity in solar active regions (sunspots and their surroundings) using the data from the National Astronomical Observatory and the magnetic field data from the Hinode satellite. In the dynamo theory, the so-called alpha effect represents convection to twist the magnetic field lines. The statistical distribution of helicity implies that the magnetic flux tubes rising through the convection zone may encounter at most one convective cell from which they acquire helicity.

Research Products

• [Int'l Joint Research] 中国科学院雲南天文台/中国科学院中国国家天文台(中国)
• [Int'l Joint Research] ロシア科学アカデミーIZMIR研究所(ロシア連邦)
• [Int'l Joint Research] 中国科学院雲南天文台/中国科学院中国国家天文台(中国)
• [Int'l Joint Research] ロシア科学アカデミーIZMIR研究所(ロシア連邦)
• [Int'l Joint Research] 中国科学院北京天文台/中国科学院雲南天文台(中国)
• [Int'l Joint Research] ロシア科学アカデミー・イズミール研究所(ロシア連邦)
• [Journal Article] Super-strong Magnetic Field in Sunspots (2018)
  • Author(s): Okamoto Takenori J., Sakurai Takashi
  • Journal Title: The Astrophysical Journal Letters Volume: 852 Issue: 1 Pages: L16-L16
  • DOI: 10.3847/2041-8213/aaa3d8
  • Peer Reviewed
• [Journal Article] Hinode's Contributions to Solar Physics (2018)
  • Author(s): Sakurai, T.
  • Journal Title: 'First Ten Years of Hinode Solar On-Orbit Observatory', Astrophysics and Space Science Library Volume: 449 Pages: 19-26
  • DOI: 10.1007/978-981-10-7742-5_2
  • ISBN: 9789811077418, 9789811077425
• [Journal Article] Infrared Spectro-Polarimeter on the Solar Flare Telescope at NAOJ/Mitaka (2018)
  • Author(s): Sakurai, T., Hanaoka, Y., Arai, T., Hagino, M., Kawate, T., Kitagawa, N., Kobiki, T., Miyashita, M., Morita, S., Otsuji, K., Shinoda, K., Suzuki, I., Yaji, K., Yamasaki, T., Fukuda, T., Noguchi, M., Takeyama, N., Yamamuro, T.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 70
  • Peer Reviewed
• [Journal Article] Statistical Study of the Magnetic Field Orientation in Solar Filaments (2017)
  • Author(s): Hanaoka Yoichiro、Sakurai Takashi
  • Journal Title: The Astrophysical Journal Volume: 851 Issue: 2 Pages: 130-130
  • DOI: 10.3847/1538-4357/aa9cf1
  • Peer Reviewed
• [Journal Article] Heating mechanisms of the solar corona (2017)
  • Author(s): Sakurai, T.
  • Journal Title: Proceedings of the Japan Academy, Series B Volume: 93 Issue: 2 Pages: 87-97
  • DOI: 10.2183/pjab.93.006
  • NAID: 130005316247
  • ISSN: 0386-2208, 1349-2896
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] On the Origin of Differences in Helicity Parameters Derived from Data of Two Solar Magnetographs (2016)
  • Author(s): Xu, H., Zhang, H., Kuzanyan, K., Sakurai, T.
  • Journal Title: Solar Physics Volume: 291 Issue: 8 Pages: 2253-2267
  • DOI: 10.1007/s11207-016-0975-1
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] The Vignetting Effect of the Soft X-Ray Telescope Onboard Yohkoh: II. Pre-Launch Data Analysis (2016)
  • Author(s): Shin,J., Sakurai, T.
  • Journal Title: Solar Physics Volume: 291 Issue: 2 Pages: 705-725
  • DOI: 10.1007/s11207-016-0845-x
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Vignetting Effect in the Soft X-Ray Telescope Onboard Yohkoh: I. Numerical Simulation (2015)
  • Author(s): Shin, J., Sakurai, T.
  • Journal Title: Solar Physics Volume: 290 Issue: 5 Pages: 1531-1546
  • DOI: 10.1007/s11207-013-0292-x
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Solar Full-Disk Polarization Measurement with the Fe I 15648 Angstrom Line (2015)
  • Author(s): Hanaoka, Y., Sakurai, T., IRMag Group
  • Journal Title: IAU Symposium Volume: 305 Issue: S305 Pages: 92-96
  • DOI: 10.1017/s1743921315004573
• [Journal Article] 太陽物理学 (2015)
  • Author(s): 桜井隆
  • Journal Title: パリティ Volume: 30 Pages: 14-15
• [Presentation] ひのでSOT/SPモザイク観測による広視野高空間分解能ベクトル磁場観測および電流ヘリシティ測定 (2018)
  • Author(s): 大辻賢一、桜井 隆、Kirill Kuzanyan
  • Organizer: 日本天文学会春季年会
• [Presentation] 「ひので」観測10年：黒点磁場強度ランキング (2018)
  • Author(s): 岡本丈典、桜井 隆
  • Organizer: 日本天文学会春季年会
• [Presentation] プロミネンスの緯度分布と太陽の周期活動 (2017)
  • Author(s): 萩野正興、桜井 隆、篠田一也、入江 誠、浜屋ひかり、石塚千彰、藤森賢一
  • Organizer: 日本天文学会秋季年会
• [Presentation] Largest Sunspots in History: Magnetic Flux Content, Emergence Rate, and Generation Mechanism (2017)
  • Author(s): Toriumi, S., Sakurai, T.
  • Organizer: Joint Hinode-11/IRIS-8 Science Meeting
  • Int'l Joint Research
• [Presentation] He I 10830Å吸収線で見たフィラメントの磁場の方向の統計的性質 (2017)
  • Author(s): 花岡庸一郎、桜井 隆、赤外マグネトグラフグループ
  • Organizer: 日本天文学会春季年会
  • Place of Presentation: 九州大学伊都キャンパス（福岡県福岡市）
• [Presentation] 「ひので」観測10年：最強の黒点磁場 (2017)
  • Author(s): 岡本丈典、桜井 隆
  • Organizer: 日本天文学会春季年会
  • Place of Presentation: 九州大学伊都キャンパス（福岡県福岡市）
• [Presentation] International Sunspot Numberの改訂と東京天文台・国立天文台の黒点相対数 (2017)
  • Author(s): 桜井 隆、藤森賢一
  • Organizer: 日本天文学会春季年会
  • Place of Presentation: 九州大学伊都キャンパス（福岡県福岡市）
• [Presentation] 太陽フレア望遠鏡赤外ポラリメーターで観測したコロナホール (2016)
  • Author(s): 萩野正興、花岡庸一郎、末松芳法、桜井隆、大井瑛仁、一本潔、大辻賢一、野澤恵、坂江隆志
  • Organizer: 日本天文学会秋季年会
  • Place of Presentation: 愛媛大学城北キャンパス（愛媛県松山市）
  • Year and Date: 2016-09-13
• [Presentation] Current Helicity in the Solar Cycle, the Properties of Turbulent Magnetic Field from Mosaic SOT/SP Raster Scans and Messages for Dynamo Theory (2016)
  • Author(s): Kuzanyan, K., Otsuji, K., Sakurai, T., Hagino, M., Yokoi, N.
  • Organizer: 10th Hinode Science Meeting
  • Place of Presentation: 名古屋大学（愛知県名古屋市）
  • Year and Date: 2016-09-05
  • Int'l Joint Research
• [Presentation] Current Helicity and Twist of Solar Magnetic Fields from Hinode/SOT SP and Ground Based Telescopes Data (2015)
  • Author(s): Otsuji, K., Sakurai, T., Kuzanyan, K., and Hagino, M.
  • Organizer: 9-th Hinode Science Meeting
  • Place of Presentation: ベルファスト市（英国、北アイルランド）
  • Year and Date: 2015-09-14
  • Int'l Joint Research
• [Presentation] 太陽の周期活動およびその長期変動と地球環境 (2015)
  • Author(s): 桜井隆
  • Organizer: 地球惑星科学連合合同大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2015-05-24
  • Invited
• [Remarks] 観測史上最強の太陽磁場
  • URL: https://www.nao.ac.jp/news/science/2018/20180206-hinode.html
• [Remarks] ダークフィラメントの磁場は半球ごとに決まった方向を向いている
  • URL: http://solarwww.mtk.nao.ac.jp/jp/topics/topics_backnumber.html