The unusual rr lyrae population of NGC 6101

Abstract

We use V-band time-series data to analyze the RR Lyrae (RRL) population of the Galactic globular cluster NGC 6101. Using template fitting, we have discovered seven new RRL stars and confirmed 10 candidates.We find unusually long mean periods for the RRL of Pab = 0.803 days and Pc = 0.393 days, and an atypically high ratio of n(c)/n(ab + c) = 0.82. Based on our derived mean properties of the RRL, NGC 6101 is Oosterhoff type II, consistent with the cluster metallicity but intriguing with respect to its kinematics. © 2011 The American Astronomical Society. All rights reserved.