A study of Upgren 1

Abstract

Upgren and Rubin (1965) have suggested that a small group of bright F stars, in the direction of the galactic north pole, may be the remnant of an old cluster. The multichannel astrometric photometer (MAP) has been used to determine the parallaxes of six of the candidate stars with an average precision of 1.1 thousandths of an arcsecond (1.1 mas). The derived distances are, as suggested, similar, and an unusual space density of F stars seems indicated. However, the derived space velocities indicate that the proposed cluster is composed of members of two dynamically different groups.