Hydrogen Lyman-alpha and Lyman-beta spectral radiance profiles in the   quiet Sun

doi:10.1051/0004-6361/200811445

CORC > 北京大学 > 地球与空间科学学院

	Hydrogen Lyman-alpha and Lyman-beta spectral radiance profiles in the quiet Sun
	Tian, H. ; Curdt, W. ; Marsch, E. ; Schuehle, U.
刊名	astronomy astrophysics
	2009
关键词	Sun: UV radiation Sun: transition region line: formation line: profiles UNRESOLVED FINE-STRUCTURES SOLAR TRANSITION REGION LY-ALPHA SOHO/SUMER OBSERVATIONS QUIESCENT PROMINENCE TEMPERATURE REGION DOPPLER SHIFTS H-I SUMER LINES
DOI	10.1051/0004-6361/200811445
英文摘要	Aims. We extend earlier work by studying the line profiles of the hydrogen Lyman-alpha and Lyman-beta lines in the quiet Sun. They were obtained quasi-simultaneously in a raster scan with a size of about 150 '' x 120 '' near disk center. Methods. The self-reversal depths of the Ly-alpha and Ly-beta profiles. we are quantified by measuring the maximum spectral radiances of the two horns and the minimum spectral radiance of the central reversal. The information on the asymmetries of the Ly-alpha and Ly-beta profiles is obtained through calculating the 1st and 3rd-order moments of the line profiles. By comparing maps of self-reversal depths and the moments with radiance images of the Lyman lines, photospheric magnetograms, and Dopplergrams of two other optically thin lines, we studied the spatial distribution of the Ly-alpha and Ly-beta profiles with different self-reversal depths, and investigated the relationship between profile asymmetries and flows in the solar atmosphere. Results. We find that the emissions of the Lyman lines tend to be more strongly absorbed in the internetwork, as compared to those in the network region. Almost all of the Ly-alpha profiles are self-reversed, while about 17% of the Ly-beta profiles are not reversed. The ratio of Ly-alpha and Ly-beta intensities seems to be independent of the magnetic field strength. Most Ly-alpha profiles are stronger in the blue horn, whereas most Ly-beta profiles are stronger in the red horn. However, the opposite asymmetries of Ly-alpha and Ly-beta are not correlated pixel-to-pixel. We also confirm that when larger transition-region downflows are present, the Ly-alpha and Ly-beta profiles are more enhanced in the blue and red horns, respectively. The first-order moment of Ly-beta, which reflects the combined effects of the profile asymmetry and motion of the emitting material, strongly correlates with the Doppler shifts of the Si III and OVI lines, while this correlation is much weaker for Ly-alpha. Our analysis shows that both Ly-alpha and Ly-beta might be more redshifted if stronger transition-region downflows are present. We also find that the observed average Ly-beta profile is redshifted with respect to its rest position.; Astronomy & Astrophysics; SCI(E); EI; 9; ARTICLE; 1; 239-248; 504
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/311304]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Tian, H.,Curdt, W.,Marsch, E.,et al. Hydrogen Lyman-alpha and Lyman-beta spectral radiance profiles in the quiet Sun[J]. astronomy astrophysics,2009.
APA	Tian, H.,Curdt, W.,Marsch, E.,&Schuehle, U..(2009).Hydrogen Lyman-alpha and Lyman-beta spectral radiance profiles in the quiet Sun.astronomy astrophysics.
MLA	Tian, H.,et al."Hydrogen Lyman-alpha and Lyman-beta spectral radiance profiles in the quiet Sun".astronomy astrophysics (2009).