Magnetic evolution and temperature variation in a coronal hole

Jun Zhang, Guiping Zhou, Jingxiu Wang, Haimin Wang

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13 Scopus citations


We have explored the magnetic flux evolution and temperature variation in a coronal hole region, using Big Bear Solar Observatory deep magnetograms and SOHO EIT images observed from 2005 October 10 to 14. For comparison, we also investigated a neighboring quiet region of the Sun. The coronal hole evolved from its mature stage to its disappearance during the observing period. We have obtained the following results: (1) When the coronal hole was well developed on October 10, about 60% of the magnetic flux was positive. The EUV brightness was 420 counts pixel-1, and the coronal temperature, estimated from the line ratio of the EIT 195 and 171 Å images, was 1.07 MK. (2) On October 14, when the coronal hole had almost disappeared, 51% of the magnetic flux was positive, the EUV radiance was 530 counts pixel-1, and the temperature was 1.10 MK. (3) In the neighboring quiet region, the fraction of positive flux varied between 0.49 and 0.47. The EUV brightness displayed an irregular variation, with a mean value of 870 counts pixel-1. The temperature was almost constant at 1.11 MK during the 5 day observation. Our results demonstrate that in a coronal hole less imbalance of the magnetic flux in opposite polarities leads to stronger EUV brightness and higher coronal temperatures.

Original languageEnglish (US)
Pages (from-to)L113-L116
JournalAstrophysical Journal
Issue number2 II
StatePublished - Feb 1 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Sun: UV radiation
  • Sun: corona
  • Sun: magnetic fields


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