The Scorpio–Centaurus Stream and the Absolute Magnitudes of the B Stars

The convergent and space motion of the Scorpio–Centaurus cluster are determined from proper motions on the N30 system and from revised radial velocities incorporating recent new observations. It is shown that the convergent is essentially at the solar antapex and the proper motions are adequately represented by standard solar motion. The new radial velocities confirm the known recession of the group from the Sun but suggest,, by their dispersion, that the moving cluster hypothesis is not tenable. Additional radial-velocity observations are required to establish the kinematical nature of the group. Application to the absolute magnitudes of the B stars is discussed. It is shown that if the group is not a moving cluster in the conventional sense a correction of +0.4 mag. is to be applied to the MK absolute magnitudes of B stars. The application of this correction brings into agreement the MK and Victoria spectroscopic absolute magnitudes of B stars.