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arXiv · 1409.6348

Radial Velocities of Three Poorly Studied Clusters and the Kinematics of Open Clusters

Christian R. Hayes·Eileen D. Friel
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Abstract

We present radial velocities for stars in the field of the open star clusters Berkeley 44, Berkeley 81, and NGC 6802 from spectra obtained using the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5 m telescope. These clusters are of intermediate age (1-3 Gyr), located within the solar Galactocentric radius, and have no previous radial velocity measurements. We find mean radial velocities of -9.6 +/- 3.0 km s^-1, 48.1 +/- 2.0 km s^-1, and 12.4 +/- 2.8 km s^-1 for Be 44, Be 81, and NGC 6802, respectively. We present an analysis of radial velocities of 134 open clusters of a wide range of ages using data obtained in this study and the literature. Assuming the system of clusters rotates about the Galactic center with a constant velocity, we find older clusters exhibit a slower rotation and larger line-of-sight (LOS) velocity dispersion than younger clusters. The gradual decrease in rotational velocity of the cluster system with age is accompanied by a smooth increase in LOS velocity dispersion, which we interpret as the effect of heating on the open cluster system over time.

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Christian R. Hayes, Eileen D. Friel. 2014-09-22. Radial Velocities of Three Poorly Studied Clusters and the Kinematics of Open Clusters. https://doi.org/10.1088/0004-6256%2F147%2F4%2F69

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