Vol 22, No 8

Spectral Behavior and Flaring Activity of II Peg in the Ultraviolet

M. R. Sanad


We have studied the spectral behavior of the II Peg 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 of II Peg was determined from a 2200 Å absorption feature to be E(B V ) = 0.10 ± 0.02. We ascertained the average mass loss rate to be ≈1 × 108 \(M_{\odot}\) yr1, and an average ultraviolet luminosity to be ≈6 × 1029 erg s1. 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.


line: profiles – magnetic fields – stars: activity – stars: flare – ultraviolet: stars

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