Cygnus OB2 at all wavelengths

Abstract

The Cygnus X region is one of the most nearby star formation regions within our Galaxy, that is recognised by prominent emission throughout the entire electromagnetic spectrum, from radio to gamma-ray waves. The centre is populated by the peculiar stellar cluster Cyg OB2, traditionally classified as OB association, but in the light of modern data more likely the prototype of a young globular cluster within our own Galaxy. Heavily shredded by dense molecular clouds this object has been less thoroughly studied than other, more distant star formation complexes in the Milky Way. I will review our current knowledge about this object, by exposing its properties and that of its environment throughout the entire electromagnetic spectrum. Particular emphasis will be given to infrared, radio-continuum, X-ray, and gamma-ray line observations that find in Cyg OB2 a text-book case for multiwavelength studies.