Fundamental Study on the Solar Tachocline towards the Long-range Forecast of the Solar Activity

2014 Fiscal Year Final Research Report

• Project/Area Number: 24740125
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Astronomy
• Research Institution: Kobe University
• Principal Investigator: MASADA Youhei 神戸大学, その他の研究科, 助教 (30590608)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 太陽 / ダイナモ / 乱流 / プラズマ物理学 / 磁気流体力学

Outline of Final Research Achievements

The origin of solar activities, such as flares and coronal-mass ejections, is the enormous magnetic energy stored in sunspots (= large-scale magnetic fields). In this research, we studied quantitatively the role of the tachocline, where is the thin interface region between the convective and radiative layers, in the solar dynamo mechanism by means of numerical simulations on state-of-the-art supercomputers. Our findings in this study are briefly summarized as follows: (1) the tachocline does not necessarily have a direct role in generating large-scale magnetic fields in the solar interior, (2) helical convective motions would rather play an essential role in organizing large-scale magnetic fields, (3) the turbulent electromotive force (specifically, the turbulent alpha effect) would be then responsible for the dynamo mechanism there, and (4) the magnetic helicity loss from the system would be a key for the polarity reversals and spatial migrations of the large-scale magnetic field.

Free Research Field

太陽天体物理学