PI: Andrea Kunder, Cerro Tololo Inter-American Observatory, firstname.lastname@example.org
Address: Casilla 603, La Serena, Chile
CoI: Roberto De Propris, Cerro Tololo Inter-American Observatory
CoI: Alistair Walker, Cerro Tololo Inter-American Observatory
Title: The Oosterhoff period shift effect in NGC1851 and NGC2808: nature or nurture ?
Abstract: We propose to measure the metallicities and period-amplitude relations of RR Lyrae with Oosterhoff I and II properties in NGC 1851 and NGC 2808. The former cluster shows a split on the subgiant branch which is likely to be due to an age difference of ~ 1 Gyr, while the latter is known to host Helium enhanced stars. Since both clusters have similar metal abundance ([Fe/H] ~ -1.2) this allows us to separate the role of age and He abundance in the origin of the Oosterhoff dichotomy.
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