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Wind-driven evolution of accreting binaries and the progenitors of SNe Ia
Received 13 January 1998 / Accepted 6 August 1998
Strong self-excited winds from the companion are very likely in many accreting binaries, and we investigate their evolutionary effects. We show that in white dwarf systems with large mass ratios , self-excited winds naturally stabilize mass transfer at a threshold value yr-1. Near this threshold value, irradiation-induced wind loss rates from the companion star become much higher, because of intermittent stable hydrogen shell burning on the accreting white dwarf. The white dwarf can accrete a substantial mass () during this evolution, and may produce a Type Ia supernova directly in some cases. In other cases the evolution may produce supersoft X-ray binaries with quite massive white dwarfs and moderate-mass companions, which then undergo thermal-timescale mass transfer and may produce SNe Ia themselves.
We show that the stability of such `bootstrap' evolution via a self-excited wind is indeterminate if the wind losses depend linearly on the mass transfer rate, as assumed in some analyses of low-mass X-ray binary evolution. Such analyses must be repeated with a more precise form of the wind-driving law. In practice systems with small mass ratios will tend to stabilize in regimes where the wind-driving law is slower than linear, with the opposite result for large mass ratios.
Key words: accretion, accretion disks stars: mass-loss novae, cataclysmic variables supernovae: general white dwarfs X-rays: stars
© European Southern Observatory (ESO) 1998
Online publication: September 17, 1998