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Post Info TOPIC: Wolf-Rayet stars


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RE: Wolf-Rayet stars
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Title: On the Eddington limit and WR Stars
Authors: André Maeder, Cyril Georgy, Georges Meynet, Sylvia Ekström

We examine some properties of stars evolving close to the classical Eddington limit for electron-scattering opacity, when these stars maintain a chemically homogeneous structure as a result of mixing and/or mass loss.
We consider analytical relations and models computed with the Geneva code. Homologous, chemically homogeneous stars evolving with a constant Eddington factor obey a relation of the form mu² M = const. This applies, for example, to Wolf-Rayet (WR) stars in stages without hydrogen. The value of the constant may depend on the metallicity, initial mass, evolutionary stage, and physical processes included in the considered homologous evolutionary sequence. An average value of the constant between 20 and 40 in solar units is consistent with the masses of Galactic WR stars.

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Wolf-Rayet stars (often referred to as WR stars) are evolved, massive stars (over 20 solar masses initially), which are losing mass rapidly by means of a very strong stellar wind, with speeds up to 2000 km/s. While our own Sun loses approximately 10-14 solar masses every year, Wolf-Rayet stars typically lose 10-5solar masses a year.
Wolf-Rayet stars are very hot, with surface temperatures in the range of 25,000 K to 50,000 K.

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Google earth file: WR Stars.kmz (18kb, kmz)



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