Figure 10: Limits of different burning regimes of accreted hydrogen onto a CO WD as a function
of mass of the WD and accretion rate [535]. If , hydrogen burns steadily.
If , H-burning shells are thermally unstable; with decrease of the strength of
flashes increases. For , hydrogen burns steadily but the excess of unburnt matter forms
an extended red-giant–sized envelope. In the latter case white dwarfs may lose matter by wind or
due to Roche lobe overflow. A dotted line shows the Eddington accretion rate as a function
of . The dashed lines are the loci of the hydrogen envelope mass at hydrogen ignition. Image
reproduced with permission from [535], copyright by AAS.