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The X-ray spectra of VW Hydri during the outburst cycle

H. W. Hartmann·P. J. Wheatley·J. Heise·J. A. Mattei·F. Verbunt
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Abstract

We report six BeppoSAX X-ray observations of VW Hydri during and after the outburst of Sep 23 1998. The outburst flux is lower than the quiescent flux in the entire observed energy band (0.1-10 keV), in agreement with earlier observations. The X-ray spectra are fitted with two-temperature plasma and cooling flow spectral models. These fits show a clear spectral evolution in X-rays for the first time in VW Hydri: the hard X-ray turn-up after the outburst is reflected in the emission measure and the temperature. Moreover, during outburst the 1.5-10 keV flux decreases significantly. We argue that this is not consistent with the constant flux during a ROSAT outburst observation made eight years earlier. We conclude from this observation that there are significant differences between outburst X-ray lightcurves of VW Hydri.

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H. W. Hartmann, P. J. Wheatley, J. Heise, J. A. Mattei, F. Verbunt. 1999-08-09. The X-ray spectra of VW Hydri during the outburst cycle. https://arxiv.org/abs/astro-ph/9908096

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