And Intermediate-mass Close Binary Evolution Of The Initial - Termination Of The Quality Of The Relationship

Binary systems have been paid much attention for many years, and the study of them may account for many perplexing problems. Binary population synthesis (BPS), which has been developed in recent years, requires the properties of binary or single star as physical inputs. Previous studies are insufficient for the development of BPS, it is therefore necessary to make a systematic investigation on the evolution of low- and intermediate-mass close binary systems.In this thesis, I have reviewed the basic scenario of binary evolution firstly. And then, the computer code for stellar structure and evolution developed by Peter P. Eggleton is introduced in detail. I carry out 150 runs of non-conservative Population I binary evolution calculations. Convective overshooting is included via 4>v(=0.12) and I assume that 50 per cent of the mass lost from the primary during RLOF is lost from the system, carrying away the same specific angular momentum as the center of mass of the primary. For the integrity of the thesis and easy comparison, the results of the conservative evolution are also shown.I find that the remnant mass depends on when RLOF begins in the HG and the dependency increases with the primary mass. However, it does not depend much on the initial mass ratio, as compared to conservative cases. For q\= 1.1,1 fit a formula for the remnant mass as a function of the initial mass M\\ of the primary and the radius of the primary at the onset of RLOF with an error less than 2.61%. Furthermore, the non-conservative models seem more stable than conservative ones whether they include convective overshooting or not. In the result of our calculations, for the models of qi = 4, RLOF is always dynamical stable as long as the initial primary mass is not very small ( ^2M?. However the RLOF of the conservative ones are all dynamical unstable in previous calculations.I have also discussed the influence of convective overshooting, which makes the final remnant masses larger (for Mli>l.6 Mo) and also makes helium and carbon burning earlier. The convective overshooting has almost no effect on low-mass binaries, consistent with previous studies. During the study, I obtained many HeCO white dwarfs with low mass (-0.33 Mo). Conservative calculations give similar result. These suggest that a low-mass CO white dwarf may be formed from stable RLOF in the HG, and therefore some of the presumed He white dwarfs observed may actually be CO white dwarfs.