Chandra X-ray Observations of the Young Stellar Cluster Berkeley 87 and its Oxygen-type Wolf-Rayet Star WR 142
- Author(s)
- Stephen Lee Skinner, Kimberley R. Sokal, Svetozar A. Zhekov, Manuel Güdel
- Abstract
Berkeley 87 is a heavily-reddened young open cluster lying in an obscured region of Cygnus. Age estimates for cluster members are typically in the range 1 - 3 Myr. Berkeley 87 is noteworthy as an example of a galactic open cluster harboring a rare oxygen-type Wolf-Rayet star, WR 142 (= Sand 5 = St 3; spectral type WO2). WO stars are the most highly-evolved WR stars and are likely supernova or gamma-ray burst (GRB) progenitors. The wind of WR 142 has a exceptionally high terminal speed in excess of 5000 km/s and may be producing shock waves in the surrounding cluster. We present results of a Chandra ACIS-I observation of Berkeley 87 centered on WR 142. The Chandra spectrum of WR 142 is exceptionally hard for a WR star, and shows excess low-energy absorption above that expected from its visual extinction. Some of this excess absorption likely arises in its powerful metal-rich wind. We compare its spectrum with the much softer X-ray spectra of cluster OB stars. We discuss the Chandra image of Berkeley 87, which reveals a large and diverse population of X-ray emitting young stars.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- University of Colorado, Boulder
- Journal
- Bulletin of the American Astronomical Society
- Volume
- 42
- ISSN
- 0002-7537
- Publication date
- 2010
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/dfc893cf-8116-4938-b66f-7bbecf1fe869