Exploring Mass Transfer Mechanisms in Symbiotic Systems

We define two regimes of the parameter space of symbiotic systems based on the dominant mass transfer mechanism. A wide range of white dwarf (WD) mass, donor mass, and donor radius combinations are explored to determine the separation for each parameter combination, below which wind Roche-lobe (RL) overflow will be the dominant mass transfer mechanism. The underlying concept is the premise that the wind accelerates. If it reaches the RL before attaining sufficient velocity to escape, it will be trapped and gravitationally focused through the inner Lagrangian point toward the accreting WD. However, if the wind succeeds in attaining the required velocity to escape from the donor’s RL, it will disperse isotropically, and the dominant mass transfer mechanism will be the Bondi-Hoyle-Lyttleton prescription, in which only a fraction of the wind will be accreted onto the WD. We present these two regimes of the 4D parameter space, covering 375 different parameter combinations.