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Wolf-Rayet and He stars (stage IV)


In the process of mass exchange, the hydrogen envelope of the star can be almost completely lost, leaving behind a hot WD for tex2html_wrap_inline9256 , or as a non-degenerate helium star   for higher masses (a WR-star in the case of a star with initial mass > tex2html_wrap_inline9178 ) as a remnant. The lifetime of a helium star   is determined by the helium nuclear burning duration (Iben and Tutukov, 1985[74])


If the helium (WR) star fills its RL (the relatively rare case ``BB'' of evolution; Delgado and Thomas (1981)[44]; see discussion in van den Heuvel (1994)[205]), the helium-rich envelope is lost and a CO stellar core remains with a mass


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