An Exosat observation of spectral variability from the RS CVn binary AR LacThe eclipsing RS CVn system AR Lac (G2IV + K0IV) has been observed continuously for one 2-day binary cycle with the Exosat observatory. Below 1 keV, a factor of two intensity modulation is seen with a flat bottomed minimum around the time of primary eclipse and a shallow dip preceeding primary eclipse. Above 1 keV, where only emission with temperatures greater than 10 exp 7 K would be detected, no orbital modulation or eclipse is seen. This suggests that the greater than 20 million degree emission comes from a large region, comparable in size to the binary separation. The modulation in the less than 1 keV lightcurve has been modeled by chi-squared fitting to X-ray bright spots and by using maximum entropy deconvolution. The lower temperature emission is found to originate in compact regions with a pressure and temperature similar to that of the flaring sun.
Document ID
19910071682
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
White, N. E. (European Space Agency. European Space Research and Technology Center ESTEC, Noordwijk, Netherlands)
Parmar, A. N. (EXOSAT Observatory Noordwijk, Netherlands)
Shafer, R. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Horne, K. (Space Telescope Science Institute Baltimore, MD, United States)
Culhane, J. L. (London, University College, Dorking, United Kingdom)