The Ebullience of High Accretion-Rate White Dwarfs

What happens when you accrete at a high rate onto a white dwarf? A. You get jets. B. You get quasi-steady thermonuclear shell burning on the white-dwarf surface. C. The white dwarf eventually approaches the Chandrasekhar limit and explodes as a Type Ia supernova. D. The white dwarf experiences outbursts that are too energetic to be disk instabilities, yet too frequent to be classical novae. E. All of the above. I will discuss option E: all of the above. As part of this discussion, I will describe observational evidence for a new type of outburst that is triggered by a sudden burst of accretion, but powered by an increase in the rate of nuclear burning on the white-dwarf surface (see Sokoloski et al. 2006) . This type of "combination nova" has in at least one case been linked with the production of jets. Furthermore, the association of classical symbiotic-star outbursts with combination novae has implications for whether the white dwarfs in symbiotic stars can gain enough mass to explode as Type Ia supernovae.

Last modified: Mon Dec 19 13:25:49 EST 2005