NIR Census Of RR Lyrae stars & Horizontal Branch Morphology in Globular Clusters

We will provide the census of Horizontal Branch (HB) and RR Lyrae stars in M2, M3, M5, M14, M15, M53, NGC 6934 Globular Clusters (GCs) in all three infrared bands J, H, and K for the first time. And give their CMDs, Bailey Diagrams and PLRs. The data for these clusters are obtained from CFHT-WIRCam. We will investigate the effect of metallicity and wavelength on HB morphology and RR Lyrae variability in GCs. More importantly, why do globular clusters with similar metallicity often show very different HB morphologies? This long-standing “second-parameter problem” will be explored using new observational data obtained from Gemini-F2, CFHT-WIRCam and theoretical models using MESA(Module for Experiments in Stellar Astrophysics) representative of HB and RR Lyrae stars in clusters of a wide range of metallicities. We will also try to study origin of a significant population of RR Lyrae stars in metal rich clusters such as NGC 6388 and NGC 6441 which are present in the bulge.