The Massive Star Forming Region Cygnus OB2. II. Integrated
Stellar Properties and the Star Formation History
N. J. Wright, J. J. Drake,
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138,
J. E. Drew
Centre for Astronomy Research, Science and Technology Research Institute, University of
Hertfordshire, Hatfield AL10 9AB, U.K.
J. S. Vink
Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, U.K.
Cygnus OB2 is the nearest example of a massive star forming region, contain-
ing over 50 O-type stars and hundreds of B-type stars. We have analysed the
properties of young stars in two fields in Cyg OB2 using the recently published
deep catalogue of Chandra X-ray point sources with complementary optical and
near-IR photometry. Our sample is complete to 1 M (excluding A and B-type
stars that do not emit X-rays), making this the deepest study of the stellar prop-