Rapid Line Variations in the Far-Ultraviolet Spectrum of 21 Com. I. The 1979 Event

Abstract

An analysis of archival IUE spectra of 21 Com revealed an instance of large and rapid flux variations on a time scale of 1 hr which occurred on November 15, 1979. Deep and broad features developed in less than 60 min and vanished in about 45 min shortwards of 1720 A. The 1979 event is thought to reflect a transient and abrupt change in the outer layers of the star and may have been occasional. Possible causes of the rapid variability in the far-ultraviolet spectrum of 21 Com are discussed.