AAS 199th meeting, Washington, DC, January 2002
Session 57. Open Clusters
Display, Tuesday, January 8, 2002, 9:20am-6:30pm, Exhibit Hall

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[57.02] WIYN Open Cluster Study: Astrometric Membership of the a Car Open Cluster

I. Platais (UBL/USRA), V. Kozhurina-Platais (STScI), T.M. Girard (Yale U.), WOCS Collaboration

Our search for new star clusters in the Hipparcos data resulted in the discovery of a promising candidate open cluster around its central star, a Car (AJ,116,2423). This probable cluster has an age and distance very similar to the Pleiades except of a very low number of known cluster members, which could be a signature of an association. This prompted us to obtain new proper motions around a Car down to V=16 using the Southern Proper Motion plate material in combination with the UCAC1 catalog. The new catalog of more than 20,000 stars reveals a presence of at least two dozen probable fainter cluster members. We argue that the astrometric data alone even if combined with photographic photometry cannot prove decisively the reality of this cluster. Therefore, an extensive program is outlined to obtain precise photometry, radial velocities, and metallicity for new probable cluster members. If finally established, the a Car cluster has a potential to provide a fresh argument in dispute on the Hipparcos Pleiades distance modulus anomaly.

This work is supported in part by NSF grant AST-0196075 to USRA.

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