New Constraints on the Origin of the Short-term Cyclical Variability of the Wolf-Rayet Star WR 46
Abstract
The Wolf-Rayet star WR 46 is known to exhibit a very complex variability pattern on relatively short timescales of a few hours. Periodic but intermittent radial velocity shifts of optical lines as well as multiple photometric periods have been found in the past. Non-radial pulsations, rapid rotational modulation, or the presence of a putative low-mass companion have been proposed to explain the short-term behavior. In an effort to unveil its true nature, we observed WR 46 with the Far Ultraviolet Spectroscopic Explorer (FUSE) over several short-term variability cycles. We found significant variations on a timescale of ~8 hr in the far-ultraviolet (FUV) continuum, in the blue edge of the absorption trough of the O VI λλ1032, 1038 doublet P Cygni profile and in the S VI λλ933, 944 P Cygni absorption profile. We complemented these observations with X-ray and UV light curves and an X-ray spectrum from archival X-ray Multi-Mirror Mission-Newton Space Telescope (XMM-Newton) data. The X-ray and UV light curves show variations on a timescale similar to the variability found in the FUV. We discuss our results in the context of the different scenarios suggested to explain the short-term variability of this object and reiterate that non-radial pulsations is the scenario most likely to occur.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2011
- DOI:
- 10.1088/0004-637X/735/1/13
- arXiv:
- arXiv:1104.4497
- Bibcode:
- 2011ApJ...735...13H
- Keywords:
-
- stars: individual: WR 46;
- stars: Wolf-Rayet;
- ultraviolet: stars;
- X-rays: stars;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 36 pages, 11 figures. Accepted for publication in ApJ