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Variation of QSO color indices with redshift

Fan, Xiao-hui; Chen, Jian-sheng

In this paper we discuss the effect of features in the spectrum of QSOs on their color indices and the consequent variation of the latter with the redshift. As the redshift increases, the various absorption features shortwards of the Lyα emission line enter into the visible region and alter the way in which the color indices vary with the redshift…

A morphological study of the circumstellar dust shell of Herbig Ae/Be stars

Wang, Jun-jie; Hu, Jing-yao

In this paper the Kurucz stellar atmosphere model is fitted to the observed IUE, IRAS, ground-based optical and near-infrared data of 22 Herbig Ae/Be stars. A statistical analysis is made based on energy balance between the central star and the circumstellar shell. It is concluded that the shells are disk-shaped.