ROSAT Detections of Symbiotic Binaries
Session 45 -- CVs/Symbiotic Stars
Display presentation, Wednesday, 1, 1994, 9:20-6:30

## [45.09] ROSAT Detections of Symbiotic Binaries

K.Bickert (Max Planck Inst., Garching), R.E.Stencel (U.Denver)

This poster reports on the results of survey and pointed observations of symbiotic binaries made with the Roentgen Satellite [ROSAT] during the sky-survey phase and AOs 2 and 3. Among the goals of the study were to determine the frequency of xray emission among symbiotics as a class of astronomical objects, and to determine, insofar as possible, their high energy variability and spectral characteristics. The symbiotic star, AG Draconis, known to exhibit optical flare-like events every few years, was re-observed several times. The initial analysis of the pointed observations suggests that only a minority of all known symbiotics were detected at the level of the ROSAT sky survey limit (f\$_x\$ \le 10\$^{-12}\$ erg cm\$^{-2}\$ s\$^{-1}\$). Further, among those objects detected, a majority showed evidence in the ROSAT observations for xray variability. Relatively few showed evidence for photons harder than about 1 keV. AG Dra may have exhibited a small flare-like event between 1992 June and September. We are pleased to acknowledge assistance by Tom Fleming and Jurgen Schmitt, as well as partial support for this effort through NASA ROSAT grant NAG5-2094 to the University of Denver.