Collaborative Research: Open Clusters at the Interface of Stellar Evolution and Stellar Dynamics

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Astronomers have long used stellar clusters to learn about the orbital motions of stars in bound groups and as laboratories for testing ideas of star formation and stellar evolution. The two fields of dynamics and stellar evolution have developed independently, but with advances in detector technology and computing speed, it is now possible to integrate these two areas of research.In this collaborative study, Dr. Robert Mathieu (University of Wisconsin - Madison) and Dr. Imants Platais (Johns Hopkins University) will undertake a series of observational and theoretical investigations to address several outstanding questions in stellar evolution and dynamics. The first objective is to obtain a comprehensive census of the single star and binary star populations in seven rich open clusters which have ages from 100 million to 7 billion years. This will be accomplished through precise measurements of minute apparent tangential motions and multi-epoch measurements of radial velocities. These data will provide highly reliable three-dimensional kinematic membership determinations for the entire evolved cluster population. The second objective is to characterize the populations of nearly 100 blue stragglers and other newly discovered anomalous stars in these clusters, focusing on their binary, rotation and stellar activity distributions. The third objective is to compute an array stellar motion simulations for open clusters with initial conditions, especially the binary population, guided by observations of young stellar clusters. The simulations will be performed in collaboration with Dr. J. Hurley (Swinburne, Australia), and Dr. A. Sills (McMaster, Canada) will collaborate on the production of anomalous stars through collisions. The union of comprehensive rotational, stellar activity and binary data for a large set of anomalous stars of different ages and masses will allow new insights on formation mechanisms, internal structures, and ages of these stars at the interface of stellar dynamics and stellar evolution.The research plan will have a broader impact through enhancement of the research and teaching skills of future astronomers, both within and beyond the borders of the United States. This research will include students and a postdoctoral fellow, and is expected to yield three graduate dissertations, several undergraduate theses, and research experiences of summer undergraduate students. This work will be associated with the Center for the Integration of Research, Teaching, and Learning, an NSF Center for Learning and Teaching directed by Mathieu. Platais, through his association with the trilateral Taiwan-Baltic collaboration, will assist in the education, training and research of students and young researchers in recently disadvantaged countries that have fast developing infrastructure and intellectual potential.