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

2017 Fiscal Year Final Research Report

• 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
• 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.

Free Research Field

太陽物理学