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 time scales 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 behaviour. In an effort to unveil its true nature, we observed WR 46 with FUSE (Far Ultraviolet Spectroscopic Explorer) over several short-term variability cycles. We found significant variations on a time scale of ~8 hours in the far-ultraviolet (FUV) continuum, in the blue edge of the absorption trough of the OVI λλ1032, 1038 doublet P Cygni profile and in the SVI λλ933, 944 P Cygni absorption profile. We complemented these observations with X-ray and UV light-curves and an X-ray spectrum from archival XMM-Newton (X-ray Multi-Mirror Mission - Newton Space Telescope) data. The X-ray and UV light-curves show variations on a time scale 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 most likely to occur.

36 pages, 11 figures. Accepted for publication in ApJ

References in corpus (6)

• On IC 10 X-1, the Most Massive Known Stellar-Mass Black Hole
• The Orbital Period of the Wolf-Rayet Binary IC 10 X-1; Dynamic Evidence that the Compact Object is a Black Hole
• CalFUSE v3: A Data-Reduction Pipeline for the Far Ultraviolet Spectroscopic Explorer
• A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1
• A Wolf-Rayet/black-hole X-ray binary candidate in NGC 300
• Excitation of g modes in Wolf-Rayet stars by a deep opacity bump

Cited by in corpus (10)

• SPIDER VIII - Constraints on the Stellar Initial Mass Function of Early-type Galaxies from a Variety of Spectral Features
• SPIDER VII - Revealing the Stellar Population Content of Massive Early-type Galaxies out to 8Re
• X-rays from Colliding Stellar Winds: the case of close WR+O binary systems
• Evolution of galaxy habitability
• Leptonic non-thermal emission from supernova remnants evolving in the circumstellar magnetic field
• The search for magnetic fields in two Wolf-Rayet stars and the discovery of a variable magnetic field in WR55
• Unlocking the secrets of stellar haloes using combined star counts and surface photometry
• A Chandra Observation of the Eclipsing Wolf-Rayet Binary CQ Cep
• Discovery of a Wolf-Rayet Star Through Detection of its Photometric Variability
• The magnetic, spectroscopic, and photometric variability of the Wolf-Rayet star WR55