Investigation of the mechanism of stellar flares by high speed spectroscopy

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H02865
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Astronomy
• Research Institution: Kyoto University
• Principal Investigator: Nogami Daisaku 京都大学, 理学研究科, 准教授 (20332728)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 恒星フレア / 太陽フレア / 黒点 / 分光観測 / 測光観測 / 多波長観測 / 磁場 / 質量放出

Outline of Final Research Achievements

We clarified in 2012 that solar-type stars could cause superflares having energies over ten times larger than that of largest solar flares observed so far, based on the data obtained by Kepler spacecraft. In this program, our analyses of data by Kepler and others exhibited that the relationship between the flare duration and energy and the emergence/decay rates of starspots are consistent with those of the Sun. This suggests common underlying physical processes between solar flares and stellar superflares. We also presented that the Halpha emission profile of an M-type star during a flare showed a continuously blue-shifted component which has not been seen in the Sun and a pre-research result of impacts of stellar superflares on exoplanet atmosphere.

Free Research Field

恒星物理学

Academic Significance and Societal Importance of the Research Achievements

今回の成果は恒星で観測されるスーパーフレアが太陽フレアと同じ物理プロセスで起こることを示唆するものであり、太陽フレアのメカニズムがこれまで考えられていたよりも4桁は大きいエネルギーでも通用することと、太陽でもスーパーフレアが起こりうることを意味する。また、スーパーフレアが惑星大気に与える影響の予備的研究成果は、将来的に太陽が地球環境や地球の生命に与えてきている研究につながるものである。