next up previous contents index
Next: Change of Binary Parameters: Up: Evolutionary Scenarios of Binary Previous: Wolf-Rayet and He stars

Stellar Winds From Normal Stars

 

The effect of the normal star on the compact magnetized component is largely determined by the rate tex2html_wrap_inline9166 and velocity of stellar wind at infinity tex2html_wrap_inline9270 . For the majority of cases, we assume

equation454

where tex2html_wrap_inline9272 is the parabolic velocity at the stellar surface.

For Be-stars (i.e. those stars at the stage ``I'' whose mass increased during the first mass exchange), the wind velocity at infinity is taken to be equal to the Keplerian velocity  at the stellar surface

equation459

Thus, the lower stellar wind velocity leads to an effective increase of the captured mass rate by a secondary companion to such Be-stars.

The stellar wind rate at stage ``I'' is calculated as (de Jager 1980[41])

equation464

Here tex2html_wrap_inline9274 is a numerical coefficient.

For giant post-MS stars (stage ``II''), we assume tex2html_wrap_inline9276 and for massive star we take maximum wind rate between that given by de Jager's formula and that given by Lamers (1981)[94]:

equation467

For red supergiants at the asymptotic giant branch (AGB) stage, we use Reimers's formula (Kudritzki and Reimers, 1978[88])

equation476

When a massive star becomes a Wolf-Rayet star, its stellar wind can significantly increase (up to tex2html_wrap_inline9278 yr tex2html_wrap_inline8853 ). We parametrize such a wind  as

equation483

where the numerical coefficient is taken to be tex2html_wrap_inline9282 .



Mike E. Prokhorov
Sat Feb 22 18:38:13 MSK 1997