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arXiv · 0908.1624

The origin of the supersoft X-ray--optical/UV flux anticorrelation in the symbiotic binary AG Draconis

A. Skopal·M. Sekeras·R. Gonzalez-Riestra·R. F. Viotti
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Abstract

AG Draconis produces a strong supersoft X-ray emission.The X-ray and optical/UV fluxes are in a strict anticorrelation throughout the active and quiescent phases. The aim of this contribution is to identify the source of the X-ray emission and reveal the nature of the observed flux anticorrelation. For this purpose we model the X-ray and UV observations with XMM-Newton, far-UV spectroscopy from FUSE, low- and high-resolution IUE spectra and optical/near-IR spectroscopic and/or photometric observations. Our analysis showed that the supersoft X-ray emission is produced by the white dwarf photosphere. The X-ray and far-UV fluxes make it possible to determine its temperature unambiguously. The supersoft X-ray--optical/UV flux anticorrelation is caused by the variable wind from the hot star. The enhanced hot star wind gives rise to the optical bursts by reprocessing high-energy photons from the Lyman continuum to the optical/UV.

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A. Skopal, M. Sekeras, R. Gonzalez-Riestra, R. F. Viotti. 2009-08-12. The origin of the supersoft X-ray--optical/UV flux anticorrelation in the symbiotic binary AG Draconis. https://doi.org/10.1051/0004-6361%2F200811418

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