Anomalous proper motions in the Cygnus superbubble region.

Abstract

In an analysis of proper motions of O and B stars contained in the Input Catalogue for Hipparcos, we have found a clear deviation from the expected pattern of systematic motions which can be readily identified with the associations Cygnus OB1 and Cygnus OB9, located near the edge of the Cygnus Superbubble. The anomalous motions are directed outwards from the center of the Superbubble, which is coincident with the association Cygnus OB2. This seems to support the hypothesis of a strong stellar and supernova activity in Cygnus OB2 giving rise to the Superbubble and, by means of gravitational instabilities in its boundaries, to Cygnus CB1 and Cygnus OB9. New uvbyβ aperture photometry of selected O and B stars in the area of Cygnus OB1 and Cygnus OB9 is also presented and analyzed in this paper.