RR Lyrae stars in M31 globular clusters: B514
Clementini, G.; Marconi, M.; Cacciari, C.; Catelan, M.; Federici, L.; Fusi Pecci, F.; Smith, H.; Contreras, R.; Merighi, R.; Kinemuchi, K.; Pritzl, B.
Italy, United States, Chile
Abstract
We present preliminary results of a variable star search in the metal-poor globular cluster B514 of the Andromeda galaxy (M31), based on Hubble Space Telescope Wide Field Planetary Camera 2 and Advanced Camera for Surveys observations. A large number of RR Lyrae stars have been identified for the first time in a globular cluster of M31. The average period of the RR Lyrae variables (< Pab > = 0.58 days and < Pc > = 0.35 days, for fundamental-mode and first-overtone pulsators, respectively) and the position in the period-amplitude diagram both suggest that B514 is likely an Oosterhoff I cluster, contrary to the general behaviour of the metal-poor globular clusters in the Milky Way, which show instead Oosterhoff type II pulsation properties.