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X-ray observations of 4 Draconis: symbiotic binary or cataclysmic triple?

Peter J. Wheatley·Koji Mukai·Domitilla de Martino
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Abstract

We present the first X-ray observations of the 4 Draconis system, consisting of an M3III giant with a hot ultraviolet companion. It has been claimed that the companion is itself an AM Her-type binary system, an identification that places strong constraints on the evolution of cataclysmic variables. We find that the X-ray properties of 4 Draconis are consistent with the presence of an accreting white dwarf, but not consistent with the presence of an AM Her system. We conclude that 4 Dra is therefore most-likely a symbiotic binary containing a white dwarf accreting material from the wind of the red giant. The X-ray spectrum of 4 Dra is sometimes dominated by partially-ionised photoelectric absorption, presumably due to the wind of the red giant. We note that X-ray monitoring of such systems would provide a powerful probe of the wind and mass-loss rate of the giant, and would allow a detailed test of wind accretion models.

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Peter J. Wheatley, Koji Mukai, Domitilla de Martino. 2003-09-15. X-ray observations of 4 Draconis: symbiotic binary or cataclysmic triple?. https://doi.org/10.1111/j.1365-2966.2003.07149.x

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