X-ray emission from symbiotic stars - not as soft as you thought they were

G. J. M. LUNA

Vina del Mar

Congreso; The Evolution of Compact Binaries; 2011

European Southern Observatory

Until recently, X-ray emission from symbiotic binaries was believed to be mainly soft or super-soft and powered either by wind-wind collision or by quasi-steady thermonuclear burning on the surface of the white dwarf. This paradigm is changing since the discovery of very hard thermal X-ray emission (E > 50 keV) from symbiotic stars powered by accretion. This hard X-ray emission is associated with an optically thin portion of the boundary layer of an accretion disc, and in analogy with other accreting white dwarfs like dwarf novae, its temperature is associated with the white dwarf mass. I will present results of the recent discovery of 12 symbiotic binaries in the hard X-ray band that suggest that their accreting white dwarfs are massive and their evolution could possibly lead them to SNIa explosions.