Abstract

We present preliminary results from a study of five globular clusters located in the Large Magellanic Cloud (LMC). The goal of this project is to carry out a large, systematic study of the behavior of RR Lyrae stars in Oosterhoff-intermediate globular clusters. The LMC is an ideal target for a study of this sort as it contains Oosterhoff-intermediate (Oo-int) clusters as well as Oosterhoff-I (Oo-I) and Oosterhoff-II (Oo-II) clusters. We seek to answer three main questions. 1.) Are there doublemode RR Lyrae stars (RRd) in Oo-int clusters and, if so, how do their properties compare to RRd stars in Oo-I/II clusters? 2.) How do the positions of RR Lyrae stars on the Bailey diagram differ between stars in Oo-int clusters and those in Oo-I/II clusters? 3.) How do the Fourier decomposition parameters of RR Lyrae stars change when going from Oo-I/II clusters to Oo-int ones? We present Oosterhoff classifications and sample light curves for some of the clusters in our study and discuss their Fourier parameters. We also discuss the implications of our findings on the nature of the Oosterhoff dichotomy and what that implies about Milky Way formation. © 2009 American Institute of Physics.