Are the O stars in WR+O binaries exceptionally rapid rotators?

Abstract

We examine claims of strong gravity-darkening effects in the O-star components of WR+O binaries. We generate synthetic spectra for a wide range of parameters, and show that the line-width results are consistent with extensive measurements of O stars that are either single or are members of `normal' binaries. By contrast, the WR+O results are at the extremes of, or outside, the distributions of both models and other observations. Remeasurement of the WR+O spectra shows that they can be reconciled with other results by judicious choice of pseudo-continuum normalization. With this interpretation, the supersynchronous rotation previously noted for the O-star components in the WR+O binaries with the longest orbital periods appears to be unexceptional. Our investigation is therefore consistent with the aphorism that if the title of a paper ends with a question mark, the answer is probably `no'.

Accepted in MNRAS

References in corpus (5)

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• The VLT-FLAMES Tarantula Survey XXI. Stellar spin rates of O-type spectroscopic binaries
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Cited by in corpus (3)

• The distance, rotation, and physical parameters of zeta Pup
• The spin rates of O stars in WR + O Magellanic Cloud binaries
• An extensive spectroscopic time series of three Wolf-Rayet stars -- II. A search for wind asymmetries in the dust-forming WC7 binary WR137