Volume 385, Number 2, April II 2002
|Page(s)||511 - 516|
|Section||Interstellar and circumstellar matter|
|Published online||15 April 2002|
The complex X-ray spectrum of the supersoft source
Astronomical Institute, Utrecht University, PO Box 80000, 3508 TA Utrecht, The Netherlands
2 SRON National Institute for Space Research, Sorbonnelaan 2, CA 3584 Utrecht, The Netherlands
3 Laboratory for High Energy Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
4 Observatoire Astronomique, UA 1280 CNRS, 11 rue de l'Université, 67000 Strasbourg, France
Corresponding author: H. Bearda, firstname.lastname@example.org
Accepted: 17 January 2002
We present the X-ray spectrum of / , obtained with the Medium Energy Grating spectrometer of the Chandra X-ray Telescope. The simplest models used by earlier authors, stellar atmospheres in combination with a thermal plasma in collisional ionization equilibrium, cannot explain the spectrum. Neither does a photo-ionized plasma. We identify P Cygni profiles of Fe XVII and O VIII, from which we conclude that these lines arise in a wind. We conclude that major uncertainty exists about the bolometric luminosity of , and perhaps of supersoft sources in general, so that the theoretical prediction that this luminosity derives from steady nuclear burning cannot be verified.
Key words: stars: atmospheres / binaries: close / line: identification / stars: individual: / stars: winds, outflows / X-rays: binaries
© ESO, 2002
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