Spectral Behavior and Flaring Activity ofⅡPeg in the Ultraviolet  

作　　者：M.R.Sanad 

机构地区：[1]Astronomy Department,National Research Institute of Astronomy and Geophysics,Helwan,Cairo,Egypt

出　　处：《Research in Astronomy and Astrophysics》2022年第8期191-197,共7页天文和天体物理学研究（英文版）

摘　　要：We have studied the spectral behavior of theⅡPeg binary system in the ultraviolet band by using International Ultraviolet Explorer(IUE)observations over the period 1979-1993.The ultraviolet observations reveal indication of flare activity in both chromosphere and transition region with their enhanced emission lines.Before and after the flare activity the ultraviolet emission lines show low,intermediate and high flux.The spectral behavior is compared with previous studies.We detect prominent flare activity in 1989,1990 and 1992.Before and after this period there is a gradual clear decrease in the level of activity.The reddening ofⅡPeg was determined from a 2200?absorption feature to be E(B-V)=0.10±0.02.We ascertained the average mass loss rate to be≈1×10^(-8)M_(☉)yr^(-1),and an average ultraviolet luminosity to be≈6×10^(29)erg s^(-1).We attributed the spectral variations to a cyclic behavior of the underlying magnetic dynamo and the prominent activity can be interpreted by the model of a two-ribbon flare.

关 键 词：line:profiles magnetic fields stars:activity stars:flare ultraviolet:stars 

分 类 号：P111[天文地球—天文学]