Spectral Behaviour and Flaring Activity of II Peg in the Ultraviolet

TL;DR

This study analyzes fifteen years of ultraviolet observations of II Peg, revealing flare activity, spectral variations linked to magnetic cycles, and estimating mass loss and luminosity, enhancing understanding of stellar magnetic phenomena.

Contribution

It provides a long-term ultraviolet spectral analysis of II Peg, identifying flare activity patterns and linking spectral variations to magnetic dynamo cycles and flare models.

Findings

Detected flare activity in three specific years.

Observed a gradual decrease in activity levels before and after flares.

Estimated mass loss rate and ultraviolet luminosity of II Peg.

Abstract

We have investigated the spectral behaviour of II Peg binary system in the ultraviolet band by using International Ultraviolet Explorer observations over fifteen years. 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 behaviour is compared with previous studies. We detect prominent flare activity in three years. Before and after this period there is a gradual clear decrease in the level of activity. The reddening of II Peg was estimated from the 2200 Angstrom absorption feature. We determined the mean rate of mass loss and the ultraviolet luminosity. We attributed the spectral variations to a cyclic behaviour of the underlying magnetic dynamo and the prominent activity can be interpreted by the model of two ribbon flare.