Flares on dMe stars : IUE and optical observations of AT MIC and comparison of far-ultraviolet stellar and solar flares.

Abstract

Observations of AT Mic obtained before and/or during a large flare on Sept. 19, 1980, using the short-wave and long-wave cameras of the IUE satellite, a UBV photometer on the 0.5-m SAAO telescope, and a 380-510-nm Cassegrain spectrophotometer on the 1.9-m SAAO telescope are reported. The data are presented in tables and graphs and compared with data for the quiescent state of AT Mic and Skylab calibrated solar UV spectra. Transition-region-line surface fluxes for the quiescent AT Mic are found to be 10-40 times those of the quiescent sun; during the flare (duration 30 min) line fluxes are enhanced by a factor of seven, with line power 10,000-100,000 times that of the solar flare observed by Skylab on June 15, 1973.