NOAO > Observing Info > Approved Programs > 2008A-0276
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NOAO > Observing Info > Approved Programs > 2008A-0276 |
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PI: Aaron M. Geller, University of Wisconsin - Madison, geller@astro.wisc.edu
Address: Astronomy Department, 475 N. Charter St., Madison, WI 53706, United States
CoI: Robert D. Mathieu, University of Wisconsin - Madison
CoI: Ella Braden, University of Wisconsin - Madison
CoI: David W. Latham, Harvard-Smithsonian CfA
Title: A Study Of Anomalous Stars and Binary Populations Within Open Clusters: Tests Of Theoretical Models
Abstract:
``Anomalous'' stars, such as blue stragglers and more recently sub-
subgiants, have been an enduring challenge for stellar evolution theory.
Recently it has become clear that in star clusters these systems are
closely linked to the binary star populations. Furthermore, through
advances in N-body modeling, we have come to realize that stellar
dynamical processes play a central role in the formation of such
anomalous stars. Indeed, these stars trace the interface between the
classical fields of stellar evolution and stellar dynamics. We propose
a thesis study to directly probe this interface through high-precision
radial-velocity measurements of the anomalous stars and the binary
populations in four open clusters. We have selected NGC 188 (7 Gyr),
M67 (NGC 2682; 4 Gyr), NGC 6819 (2.4 Gyr), and M35 (NGC 2168; 150 Myr),
as these span a wide range in age, are rich enough to provide
statistically significant conclusions, and already have an extensive
base of kinematic, spectroscopic, and photometric observations from the
WIYN Open Cluster Study. Our proposed observations will define the
spectroscopic hard binary populations (fraction, frequency distributions
of orbital parameters, mass ratios) for orbital periods approaching the
hard-soft boundary. These observations will also provide a
comprehensive survey for anomalous stars, including secure establishment
of their cluster membership. These data will allow us to perform the
first detailed comparison to predictions from open cluster simulations
of the binary populations among normal and anomalous stars, and thereby
to constrain the evolutionary paths from one to the other.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2008A-0276 |
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