CONDITIONS FOR ACCRETION-INDUCED COLLAPSE OF WHITE-DWARFS

Recent discovery of an unexpectedly large number of low-mass binary pulsars (LMBPs) in globular clusters has instigated active discussions on the evolutionary origin of binary pulsars. Prompted by the possibility that at least some of LMBPs originate from accretion-induced collapse (AIC) of white dwarfs, we reexamine whether or not AIC occurs for the new models of O + Ne + Mg white dwarfs and solid C + O white dwarfs that can ignite explosive nuclear burning at significantly lower central densities than in the previous models. We find that even with low densities, AIC is still much more likely than explosion for both types of white dwarfs. We present possible regions for AIC in a diagram of mass accretion rate versus initial mass of the white dwarf.