The Global Kinematics of the Globular Cluster M92

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Show simple item record Drukier, G.A. Cohn, H.N. Lugger, P.M. Slavin, S.D. Berrington, Robert C. Murphy, B.W. 2020-01-31T15:02:54Z 2020-01-31T15:02:54Z 2/7/2007
dc.identifier.citation Drukier, G.A., Cohn, H.N., Lugger, P.M., Slavin, S.D., Berrington, R.C., and Murphy B.W. (2007)The Global Kinematics of the Globular Cluster M92. The Astonomical Journal. 113. 1041. en_US
dc.description.abstract We report the determination of high-accuracy radial velocities for 306 members of the globular cluster M92 using the Hydra multiobject spectrograph on the WIYN telescope. We have concentrated on stars outside of the central region of the cluster, located up to 14.4&arcmin; from the cluster center. Candidate members were selected for spectroscopy based on a photometric metallicity index determined from three-band Washington photometry, also obtained with the WIYN telescope. The median error in the velocities is 0.35 km s-1. We find the heliocentric radial velocity of the cluster to be -121.2 ± 0.3 km s-1. We have used an improved Bayesian analysis to determine the velocity dispersion profile of M92. The most probable profile is a cored power law with a scale radius of 2&arcmin;, a velocity dispersion at 1&arcmin; of 6.3 km s-1, and an outer power law with a slope of -0.6. We have also reanalyzed the M15 radial velocities of Drukier et al. and find that a pure power law with a 1&arcmin; velocity dispersion of 8 km s-1 and a slope of -0.5 and the combination of a power law with a slope of -0.4 and a scale of 7.5 km s-1 inside 9&arcmin; and a dispersion of 4 km s-1 outside are equally likely. In both clusters there is evidence that the samples include escaping stars. We present results from a GRAPE-based N-body simulation of an isolated cluster that demonstrates this effect. We suggest additional tests to determine the relative importance of tidal heating and stellar ejection for establishing the velocity field in globular cluster halos. en_US
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dc.relation.isversionof en_US
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dc.subject globular clusters: individual (M92 M15) en_US
dc.subject methods: statistical en_US
dc.subject stellar dynamics en_US
dc.title The Global Kinematics of the Globular Cluster M92 en_US
dc.type Article en_US
dc.rights.holder (c) 2007. The American Astronomical Society

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