Goals of the WYIN Open Cluster Survey (WOCS)
Star clusters are superb astrophysical laboratories containing cospatial and coeval samples of stars with similar composition. Open clusters are particularly valuable as they span a wide range of age, metallicity, richness, and galactic radius. As such open clusters are the observational foundation for stellar astrophysics, provide essential tracers of galactic structure and evolution, and are unique stellar dynamical environments. Indeed there are few fields in astrophysics that do not in some way rely on results derived from open cluster studies.
Recent advances in instrumentation are driving a renaissance in the study of open clusters. Members of the WIYN collaboration have initiated the WIYN Open Cluster Study, or ''WOCS'', a project dedicated to comprehensive photometric, astrometric, and spectroscopic studies of a select set of open clusters spanning the range of age and metallicity. The goals of WOCS are two:
Comprehensive and definitive photometric, spectroscopic, and astrometric databases for new fundamental clusters.
A handful of thoroughly studied open clusters - for example, the Hyades, the Pleiades, NGC 752, and M67 - have repeatedly provided the foundation for numerous fields of stellar astrophysics. The WIYN telescope furnishes an opportunity to expand this set of fundamental clusters, and in particular to provide extensive spectroscopic analyses of superb clusters at larger apparent distance moduli. A goal of WOCS is to expand by a factor of several the ranks of fundamental clusters which provide the foundation of stellar astrophysics.
A body of investigations which address critical astrophysical problems through study of open clusters.
Subjects under active investigation within WOCS include: detailed testing of core convective overshoot and implications for stellar lifetimes; photometric monitoring of periods for study of angular momentum evolution; delineation of faint main sequences to test stellar evolution theory of very low mass stars; discovery of white dwarf sequences as independent dating mechanisms; Fe, CNO and Li abundance analyses for studies of internal stellar processes (mixing, diffusion, mass loss, etc), Galactic chemical evolution, and primordial abundances; binary populations; stellar evolution in close binary environments; initial and present-day mass functions; and stellar dynamics in clusters with rich binary populations.