Simultaneous Exosat and VLA Observations of the W UMa Binaries, VW Cep and XY Leo: A Flare on VW Cep
We have observed two W UMa-type contact binaries, XY Leo and VW Cep, simultaneously with EXOSAT, the VLA, and, in the case of XY Leo, optically. The temporal coverage of each star was sufficient to monitor them throughout two orbital revolutions (P~0.25 days), however, no orbital modulation of either the X-ray or 6 cm data was seen for either star. A large flare from VW Cep was detected, the first such simultaneous flare ever seen on a star other than the Sun. Its behavior before, during, and after the flare is remarkably similar to that found in solar flares. For both stars, it is demonstrated that the 6 cm emission cannot be the result of Bremsstrahlung radiation of the X-ray emitting plasma.
KeywordsSolar Flare Impulsive Phase Orbital Modulation Orbital Revolution Large Flare
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- Mewe, R. 1986, private communication.Google Scholar