From the Sun to the Stars: Theoretical and Observational Approaches to Understand Solar/Stellar Activities

Shin Toriumi（鳥海 森）
ISAS/JAXA 太陽系科学研究系

The Sun and stars have common magnetic activity phenomena, as represented by flares and coronal mass ejections that occur in highly magnetized active regions. This year (the third year as an ITYF), I conducted research to investigate the universality of atmospheric heating in the Sun and solar-like stars. The central issue is whether the same atmospheric heating mechanism occurs in other stars with different activities from the Sun. To this end, we systematically surveyed the response of the solar atmospheres to the surface magnetic flux over a wide range of temperatures. Analyzing 10 years of multi-wavelength synoptic observations of the Sun reveals the power-law proportionalities between irradiances and magnetic flux, in which the power-law exponent decreases from above- to sub-unity as the temperature drops from the corona to the chromosphere. In addition, this tendency showing the efficiency of atmospheric heating can be extended to sun-like stars. This study provides observational evidence that the mechanism of atmospheric heating is universal between the Sun and stars, regardless of age or activity. In the ITYF seminar, I will report on the research activity in FY2021 with mainly focusing on the above study.

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