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A 2.3 Day Periodic Variability in the Apparently Single Wolf-rayet Star Wr 134 : Collapsed Companion or Rotational Modulation?
| Content Provider | Semantic Scholar |
|---|---|
| Author | Rj, Elliott Fj, Mostert Thomas H. |
| Copyright Year | 1999 |
| Abstract | The apparently single WN 6 type star WR 134 (HD 191765) is distinguished among the Wolf-Rayet star population by its strong, presumably cyclical (PB 2.3 day) spectral variations. A true periodicityÈ which is still very much debatedÈwould render WR 134 a prime candidate for harboring either a collapsed companion or a rotating, large-scale, inhomogeneous outÑow. We have carried out an intensive campaign of spectroscopic and photometric monitoring of WR 134 from 1989 to 1997 in an attempt to reveal the true nature of this object. This unprecedentedly large data set allows us to conÐrm unambiguously the existence of a coherent 2.25^ 0.05 day periodicity in the line-proÐle changes of He II j4686, although the global pattern of variability is di†erent from one epoch to another. This period is only marginally detected in the photometric data set. Assuming the 2.25 day periodic variability to be induced by orbital motion of a collapsed companion, we develop a simple model that aims to investigate (1) the e†ect of this strongly ionizing, accreting companion on the Wolf-Rayet wind structure, and (2) the expected emergent X-ray luminosity. We argue that the predicted and observed X-ray Ñuxes can only be matched if the accretion on the collapsed star is signiÐcantly inhibited. Additionally, we performed simulations of line-proÐle variations caused by the orbital revolution of a localized, strongly ionized wind cavity surrounding the X-ray source. A reasonable Ðt is achieved between the observed and modeled phase-dependent line proÐles of He II j4686. However, the derived size of the photoionized zone substantially exceeds our expectations, given the observed low-level X-ray Ñux. Alternatively, we explore rotational modulation of a persistent, largely anisotropic outÑow as the origin of the observed cyclical variability. Although qualitative, this hypothesis leads to greater consistency with the observations. Subject headings : stars : individual (WR 134) È stars : mass loss È stars : Wolf-Rayet |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.astro.ulg.ac.be/~morel/articles/ApJ_518_428.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
