ASCA Observations of 441 Bootis and VW Cephei
Abstract
We present X-ray light curves and the energy spectra obtained from the ASCA observations of the W UMa-type binary systems, 44i Boo and VW Cep. We find that the spectra of both systems require a variable abundance plasma model having two different temperatures, kT ~0.6 - 0.7 keV and ~1.8 - 2.0 keV, to be fitted acceptably. During the observation of VW Cep, we detect a flare which shows a rapid rise of X-ray flux from 0.35 counts/s to about 1 counts/s followed by a monotonic decrease on timescale of ~5 hours. A dip is overlayed on the light curve near orbital phase of 0.5. We consider the flux dip as due to an eclipse because the orbital phase of the dip coincides well with a secondary eclipse expected from an optical data. We also find significant flux variations from 44i Boo between ~1.1 and ~1.4 counts s-1. The variation is erratic and shows neither orbital phase dependence nor energy dependence clearly.
- Publication:
-
The Hot Universe
- Pub Date:
- 1998
- Bibcode:
- 1998IAUS..188..226C