Multiple Rings and the Evolution of Wolf-Rayet Stars

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Session 83 -- Circumstellar Gas and Dust
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[83.09] Multiple Rings and the Evolution of Wolf-Rayet Stars

A. P. Marston (Steward Obs. \& Drake University)

We present both far-infrared and narrow-band optical images showing evidence of multiple concentric rings of material around Wolf-Rayet stars. The multiple rings show evidence for a three phase evolution, with massive O stars creating large, wind-blown cavities. The cavities are partially filled with stellar ejecta as these stars pass through a red supergiant or luminous blue variable mass-loss stage. The Wolf-Rayet stars then produce wind-blown bubbles inside the stellar ejecta. A simple model allows estimates of lifetimes for each of the stages which are consistent with theoretical expectations. We predict large masses for the ejecta in our multiple ring nebulae, consistent with the total mass-loss required for O stars of $>$40M$_{\odot}$ to become Wolf-Rayet stars. Finally, we illustrate how further observations of multiple ring nebulae will allow the determination of many of the parameters of massive star evolution, such as the average mass-loss rates in various phases and the surface abundance changes with time. \par This work was partially supported by NASA JOVE grant NAG8-264 and Research Corporation grant C-3054.

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