Can the gamma-ray source 3EG J2033+4118 be produced by the stellar system Cygnus OB2 No.5?

Citation
P. Benaglia et al., Can the gamma-ray source 3EG J2033+4118 be produced by the stellar system Cygnus OB2 No.5?, ASTRON ASTR, 366(2), 2001, pp. 605-611
Citations number
51
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
0004-6361 → ACNP
Volume
366
Issue
2
Year of publication
2001
Pages
605 - 611
Database
ISI
SICI code
0004-6361(200102)366:2<605:CTGS3J>2.0.ZU;2-R
Abstract
We discuss the possibility that the stellar system Cyg OB2 No.5 can be a ga mma-ray source in the light of recent EGRET and radio data. This system is formed by an O7 Ia + Ofpc/WN9 contact binary. A third star, probably a B0 V star also associated with the system, is located at similar to 1700 AU fro m the primary. We estimate the expected gamma-ray luminosity from the colli ding winds region, the terminal shock of the wind, and the unstable zone at the base of the wind, and conclude that, undervery reasonable assumptions, Cyg OB2 No.5 can generate about a half of the gamma-ray flux detected from the positionally coincident source 3EG J2033+4118. We suggest, then, that other O stars belonging to the association, also placed within the 95% prob ability EGRET location contour, could contribute to the observed gamma-ray flux.