Collaborative Project: Deep Astrometry and Photometry of Key Open Clusters: A New Foundation For Stellar Astrophysics

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ABSTRACTSarajedini, Ata"Collaborative Project: Deep Astrometry and Photometry of Key Open Clusters: A New Foundation for Stellar Astrophysics"AST-9819768This is a multi-pronged collaborative investigation of stellar open clusters with Imants Platais at Yale University (AST-9819777). The goal is to provide useful clues and constraints on a variety of astrophysical problems such as: (1) the shape of the Initial Mass Function and its universality; (2) the extent of convective overshoot in stellar cores; and (3) the metallicity gradient in the Galaxy. The project will also result in a database of high quality astrometric, photometric and spectroscopic data for a carefully chosen sample of open clusters that will provide a benchmark for many unrelated future studies. This grant supports the photometry portion of this investigation. UBVRI apparent magnitudes and color indices for cluster members will be obtained to ~1% internal precision for all stars in the astrometric database, as well as for fainter stars in these 8 clusters and 6 additional clusters. The collaborating team will conduct the astrometry portion of this investigation. Positional information, proper motions and cluster membership determinations will be acquired for 8 key open clusters to at least 6 apparent magnitudes (~250x) fainter than previous surveys, while maintaining current limits of proper motion accuracy (~0.005 "/yr). From this data, the present distribution of stars by mass will be determined for a wide range of cluster ages, richness, galactic position and metallicity.