천문학회지 (Journal of The Korean Astronomical Society)

  • 제55권2호
  • /
  • Pages.59-66
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  • 2022
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  • 1225-4614(pISSN)
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  • 2288-890X(eISSN)
한국천문학회 (The Korean Astronomical Society)
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STELLAR MAGNETIC ACTIVITY MEASURE BASED ON IUE MG II H+K EMISSION LINES OF MAIN-SEQUENCE G STARS

  • Kim, Dowoon (Department of Astronomy and Space Science, Chungnam National University) ;
  • Choi, Hwajin (Department of Astronomy and Space Science, Chungnam National University) ;
  • Yi, Yu (Department of Astronomy and Space Science, Chungnam National University)
  • 투고 : 2021.04.08
  • 심사 : 2022.04.12
  • 발행 : 2022.04.30
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초록

Stellar magnetic activity is important for formulating the evolution of the star. To represent the stellar magnetic activity, the S index is defined using the Ca II H+K flux measure from the Mount Wilson Observatory. Mg II lines are generated in a manner similar to the formation of Ca II lines, which are more sensitive to weak chromospheric activity. Mg II flux data are available from the International Ultraviolet Explorer (IUE). Thus, the main purpose of this study was to analyze the magnetic activity of stars. We used 343 high-resolution IUE spectra of 14 main-sequence G stars to obtain the Mg II continuum surface flux and Mg II line-core flux around 2,800 Å. We calculated S index using the IUE spectra and compared it with the conventional Mount Wilson S index. We found a color (B - V ) dependent association between the S index and the Mg II emission line-core flux. Furthermore, we attempted to obtain the magnetic activity cycles of these stars based on the new S index. Unfortunately, this was not successful because the IUE observation interval of approximately 17 years is too short to estimate the magnetic activity cycles of G-type stars, whose cycles may be longer than the 11 year mean activity cycle of the sun.

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과제정보

This work was supported by the research fund of Chungnam National University.

참고문헌

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