Spectral behavior and Flaring Activity of II Peg in the Ultraviolet

Abstract

Abstract We have investigated the spectral behavior of II Peg binary system in the ultraviolet band by using International Ultraviolet Explorer (IUE) observations over the period (1979 – 1993). The ultraviolet observations show indication of flare activity in the chromosphere and transition region with their enhanced spectral lines. Before and after the flare activity the ultraviolet spectral lines show low, intermediate and high flux. The spectral behavior is compared with previous studies. We detect prominent flare activity in (1989, 1990, 1992). Before and after this period there is a gradual clear decrease in the level of activity. The reddening of II Peg was estimated from 2200 Å absorption feature to be E (B-V) = 0.10 ± 0.02. We determined the mean rate of mass loss to be ~ 1 × 10-8 M yr-1, the mean temperature of the emitting source to be ~ 1.1 × 104 K, and the ultraviolet luminosity to be ~ 7 × 1027 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 two – ribbon flare.