Investigating the origin of the spectral line profiles of the Hot Wolf-Rayet Star WR2

Abstract

The hot WN star WR2 (HD6327) has been claimed to have many singular characteristics. To explain its unusually rounded and relatively weak emission line profiles, it has been proposed that WR2 is rotating close to break-up with a magnetically confined wind. Alternatively, the line profiles could be explained by the dilution of WR2's spectrum by that of a companion. In this paper, we present a study of WR2 using near-infrared AO imaging and optical spectroscopy and polarimetry. Our spectra reveal the presence of weak photospheric absorption lines from a ~B2.5-4V companion, which however contributes only ~5-10% to the total light, suggesting that the companion is a background object. Therefore, its flux cannot be causing any significant dilution of the WR star's emission lines. The absence of intrinsic linear continuum polarization from WR2 does not support the proposed fast rotation. Our Stokes V spectrum was not of sufficient quality to test the presence of a moderately strong organized magnetic field but our new modelling indicates that to confine the wind the putative magnetic field must be significantly stronger than was previously suggested sufficiently strong as to make its presence implausible.

12 pages, 9 figures

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Cited by in corpus (4)

• The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters
• Unlocking Galactic Wolf-Rayet stars with $\text{Gaia}$ DR2 I: Distances and absolute magnitudes
• A spectroscopic multiplicity survey of Galactic Wolf-Rayet stars. I. The northern WC sequence
• Unlocking Galactic Wolf-Rayet stars with $\text{Gaia}$ DR2 II: Cluster and Association membership