Study of structural variation of the global heliosphere associated with the peculiar solar dynamo activity

2017 Fiscal Year Final Research Report

• Project/Area Number: 25247079
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Space and upper atmospheric physics
• Research Institution: Nagoya University
• Principal Investigator: Tokumaru Munetoshi 名古屋大学, 宇宙地球環境研究所, 教授 (60273207)
• Co-Investigator(Renkei-kenkyūsha): FUJIKI Ken'ichi 名古屋大学, 宇宙地球環境研究所, 助教 (20303597)
• Research Collaborator: HAYASHI Keiji 名古屋大学, 宇宙地球環境研究所, 特任助教 ; MARUYAMA Yasushi 名古屋大学, 宇宙地球環境研究所, 技術職員 ; MARUYAMA Kazuo 名古屋大学, 宇宙地球環境研究所, 技術補佐員 ; IJU Tomoya 名古屋大学, 理学研究科, 大学院生
• Project Period (FY): 2013-04-01 – 2018-03-31
• Keywords: 太陽風 / 惑星間空間シンチレーション / 太陽圏 / 宇宙天気 / 太陽ダイナモ

Outline of Final Research Achievements

We carried out interplanetary scintillation measurements using the improved multi-station system of the Nagoya University in order to elucidate the global distribution of the solar wind and its evolution during the Solar Cycle 24 associated with extremely weak activities. As the result, we find that the occurrence of the very slow (< 350 km/s) solar wind, whose density is as low as the fast wind, increases distinctly in this cycle, and that the relation between the speed and either the open field areas or the magnetic flux expansion factor does not show any clear response to the solar activity. These facts suggest that the mass supply or energy injection rate from the corona decreases in association with a marked decline of the solar activity, and the fact that this effect is most prominent for the very slow wind provides an important clue to the solar wind acceleration.

Free Research Field

惑星間空間物理学