University of Wisconsin

Space Astronomy Laboratory

ASTRO - 2

WUPPE PROGRAM CLASS 2.3

WOLF-RAYET STARS

Objects:
#2302 EZ Canis Majoris (EZ-CMA), HD 50896
#2307 Theta Muscae (THT-MUS), HD 113904
#2311 Wolf-Rayet 135, HD 192163
#2313 Wolf-Rayet 140, HD 193793
UW Astronomer: Geoff Fox


Rare Wolf-Rayet stars are thought to represent one of the final phases of evolution of massive OB stars. They are extremely bright stars with luminosities between 100,000 and 1,000,000 times that of the Sun and temperatures up to 100 times greater. Unlike our quiet Sun with its weak solar wind, Wolf-Rayet stars have powerful, eroding stellar winds that have hastened their evolution, causing what may have been very hot, massive, luminous stars to become less and less massive throughout their lives.

The geometry of Wolf-Rayet stars is being studied by the WUPPE scientists. These stars possess strong winds carrying electrons that cause the radiation from the system to swing in one direction - to be polarized - rather than oscillating in all different directions if the shape of the wind is not spherically symmetric. This polarization of the light can tell astronomers about the properties of the stellar winds emerging from these stars.