Journal of The Korean Astronomical Society (천문학회지)
- Volume 33 Issue 1
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- Pages.57-73
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- 2000
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- 1225-4614(pISSN)
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- 2288-890X(eISSN)
NONTHERMAL BROADENING OF UV LINES OBSERVED AT THE LIMB OF THE QUIET SUN
- LEE HVUNSOOK (Astronomy program, School of Earth and Environmental Sciences, Seoul National University) ;
- YUN HONG SIK (Astronomy program, School of Earth and Environmental Sciences, Seoul National University) ;
- CHAE JONGCHUL (Big Bear Solar Observatory)
- Published : 2000.04.01
Abstract
We have done a spectroscopic study of the solar transition region using high resolution UV & EUV data obtained by SUMER(Solar Ultraviolet Measurements of Emitted Radiation) on board SOHO(Solar and Heliospheric Observatory). Optically thin and conspicuous emission lines observed at the solar limb are carefully selected to acquire average values of physical parameters for the quiet region as a function of radial distance. Our main results found from the present study can be summarized as follows. 1) Nonthermal velocities estimated from various UV lines do not decrease with height at least within one total line intensity scale height above the limb. 2) Nonthermal velocity distribution with temperature is very similar to that of the disk center, in the sense that its peak is located around