SIMBAD references

Some aspects of the structure and kinematics of the local system of young objects, dominated by the Gould Belt, are examined using an extended sample of O and B stars. Its orientation, extent, age, and stellar mass are evaluated by means of a statistical separation of the components of the Belt from the rest of the galactic disk in the solar neighbourhood. We have carried out different determinations of the Oort constants for our stellar sample. No extreme differences from the values usually accepted for a differentially rotating galactic disk are found, and our results suggest that the kinematics of early type stars is dominated by galactic rotation even at a local scale. The structure of the well known local expansion is deduced from the observed trends in the Oort constants; our results indicate that this expansion takes place from a line, rather than from a single point. This is found to be in agreement with our model for the origin of the Gould Belt, presented in a previous paper.