Correlation Height of the Emission Source of Si Ⅱ in a Coronal Hole Region
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摘要: SiⅡ辐射线源区的高度表征了太阳大气过渡区的底层高度.通过对超紫外线的辐射强度结构和无力场外推所得的三维磁场结构作相关分析来求相关高度是一种研究超紫外辐射线源区高度的新方法.有研究发现,该方法得到的冕洞区SiⅡ辐射线源区的高度比传统观点所认为的高.由于目前运用该方法的数据分析有限,需要用更多的数据进一步验证这一结果.运用该方法分析了SOHO/SUMER观测到的位于太阳南极冕洞之下的日面区域SiⅡ辐射线数据和美国National Solar Observatory/Kitt Peak(NSO/KP)测量的磁场数据,得到冕洞区SiⅡ辐射线源区的相关高度约为5.0 Mm.该结果支持了冕洞区的过渡区底层高度比宁静区的要高的结论.同时发现了新的现象,并对其原因进行推测.Abstract: The height of the source for Si Ⅱ represents the altitude of the bottom of the solar transition region. It is a new method to determine the so-called correlation height, by correlating the radiance of the FUV/EUV line with the magnetic field from a force-free extrapolation, as the height of the FUV/EUV emission source. A previous study found that the height of the source for SiⅡdetermined by applying this method in a coronal hole region is higher than that in the traditional view, which is so limited that it requires more data analysis to check. Using this method, the radiance data of SiⅡ, obtained in a south coronal hole region of the Sun by SOHO/SUMER, and the photospheric magnetic field, measured by NSO/KP (National Solar Observatory/Kitt Peak), were analyzed. And the correlation height of SiⅡ is determined to be about 5.0 Mm for the data sets selected from a south coronal hole region. This result supports the recent conclusion that the bottom of the transition region in the coronal hole region is quite higher than that in the quiet-Sun region. Besides, a little difference from the previous study is found and the reason for this is speculated.
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Key words:
- Transition region /
- Coronal hole /
- Extreme-ultraviolet emission
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