Radius-Evolution of Helium Accreting CO-White Dwarf

Radius of a CO-White Dwarf which accretes helium at a constant rate of 10**-6 solar masses per year, as function of its (growing) mass. The assumed initial white dwarf mass is 0.8 solar masses. As long as the white dwarf mass is smaller than 1.02 solar masses, the white dwarf burns the helium stably. But the burning becomes thermally unstable at larger mass, showing thermal pulses whose amplitude is growing in time. After about 50 thermal pulses, at a mass of about 1.04 solar masses (the end of our evolutionary sequence) the white dwarf reaches its Eddington-limit during a thermal pulse. This model, as a typical case, will have problems to ever reach the Chandrasekhar mass and produce a Type Ia Supernova. Find more details in our paper in Astronomy and Astrophysics Vol. 362, pp. 1046-1064 (2000), or in Silvia Scheithauer's Master Thesis here .