Photometry and Spectroscopy of Old, Outer Disk Star Clusters: vdB-Hagen 176, Berkeley 29, and Saurer 1

It has been previously proposed that some distant open clusters in the MilkyWay may have been accreted during a dwarf galaxy merger, perhaps associatedwith the same event that led to the formation of the Galactic anticenterstellar structure (GASS), also known as the ``Monoceros Ring''. We haveobtained VI and Washington+DDO51 photometric and medium resolution (R ~ 8000)multi-fiber spectroscopic data for the three distant old open clusters Berkeley29, Saurer 1, and vdB-Hagen 176 (BH 176). These clusters are spatiallycoincident with GASS, but radial velocities and spectroscopic metallicities hadnot been available during previous studies of the GASS candidate clustersystem. Similar data for the clusters Berkeley 20 and Berkeley 39 have beenobtained for calibration purposes. We provide the first {\it reliable} radialvelocity for BH 176 (V_{helio} = 11.2 +/- 5.3 km/s). We also find thatV_{helio} = +95.4 +/- 3.6 and +28.4 +/- 3.6 km/s, for Saurer 1(A) and Berkeley29, respectively. We show that alpha-enhanced isochrones, whilespectroscopically motivated, provide a poor fit to Be29 in contrast to previousfindings. We find that the clusters Berkeley 29 and Saurer 1 are consistentwith the previously reported characteristics for GASS candidate clustersand theGASS stellar stream as derived from M-giant observations. However, the radialvelocity and photometric metallicity ([Fe/H] ~ 0.0 dex) for BH 176 suggeststhat a connection of this cluster with the putative GASS cluster system isunlikely. We reassess the age-metallicity relation for the most likely membersof the GASS clusters system for which spectroscopic metallicities are nowavailable.Comment: 15 pages, 14 figures, AJ accepte