Ultraviolet emission lines and optical photometry of the flare star AT Microscopii.
Linsky, J. L.; Marang, F.; Ayres, T. R.; Ambruster, C.; Engvold, O.; Elgaroy, O.; Jensen, E.; Joras, P.; Clark, M.; Pettersen, B. R.; Kunkel, W.
Norway
Abstract
Ultraviolet spectra of the dwarf flare star binary AT Mic (dM 4.5e+dM 4.5e) were obtained with the IUE spacecraft on three days in September 1985. A high-resolution short-wavelength spectrum was exposed for 25 hours. Simultaneous optical monitoring in the U-band was performed during part of the IUE observations. At the time of observation AT Mic was flaring at an average rate of 1.3 flares per hour. On the average 9% of the energy in the U-band was due to the detected flare activity. From the observed high resolution spectra, line wavelengths, widths and fluxes were derived, and the effects of the binary structure of AT Mic on the spectral lines were evaluated. The ultraviolet emission line spectrum is similar in character to that of flare regions on the Sun and other stars.