The Wolf-Rayet System WR 147: A Binary Radio Source with Thermal and Nonthermal Components
Abstract
A revised distance of 630 pc is derived for WR 147(WN8) from new high resolution near-infrared images, indicating that WR 147 is not associated with the Cyg OB2 association as previously thought. VLA images of WR 147 at three different epochs show two radio components separated by 0.58 arcsec in an approximately N-S direction. Optical astrometry shows that WR 147 coincides with the southern radio component WR 147S whose spectrum and visibility function are consistent with a thermal wind. The northern radio component WR 147N is clearly nonthermal. The radio emission from WR 147S can be accurately modeled by a spherical wind whose density decreases with distance as r exp -2. An average mass-loss rate of 4.2 +/- 0.2 x 10 exp -5 solar masses/yr and a mean wind temperature of 9400 +/- 1000K are derived. The only mechanism found that could produce the observed X-ray luminosity is gravitational capture by a neutron star orbiting in a dense, slow equatorial wind from WR 147S. This result lends support to a magnetic rotator model, though shocks in the wind of WR 147 or perhaps colliding winds from WR 147S and WR 147N could also produce X-ray emission.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1992
- DOI:
- 10.1086/171508
- Bibcode:
- 1992ApJ...393..329C
- Keywords:
-
- Near Infrared Radiation;
- Radio Emission;
- Stellar Winds;
- Wolf-Rayet Stars;
- Angular Resolution;
- Astrometry;
- Stellar Luminosity;
- Very Large Array (Vla);
- Astrophysics;
- RADIO CONTINUUM: STARS;
- STARS: BINARIES: VISUAL;
- STARS: WOLF-RAYET