NOAO >   Observing Info >   Approved Programs >   2002B-0280

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Proposal Information for 2002B-0280


PI: Lucas Macri, Harvard-Smithsonian CfA, lmacri@cfa.harvard.edu
Address: 60 Garden St, Cambridge, MA 02138, USA

CoI: Dimitar Sasselov, Harvard-Smithsonian CfA
CoI: Krzysztof Stanek, Harvard-Smithsonian CfA

Title: Improving the Cepheid Distance Scale

Abstract: We propose to improve the Cepheid Distance Scale through a study of one of its leading systematic uncertainties: the metallicity dependence of the Cepheid Period-Luminosity relation. We have recently completed a survey for variable stars in M33, covering over 1000 \sq \arcmin. We have discovered approximately 700 Cepheids that span a range in metal abundance of over 1 dex. This makes our sample of variables ideally suited for a study of the metallicity dependence of the Cepheid P-L relation. We propose to obtain a data set of unprecedented photometric quality and wavelength coverage, with modest phase coverage, to study this effect. Given our existing knowledge of the positions and periods of the variables, only a minimal amount of telescope time is required to obtain high-quality light curves. This study will result in an accurate and precise characterization of the metallicity dependence of the Cepheid Period-Luminosity relation across the optical and near-infrared, sensitive to any values of this effect that would be of importance for the Extragalactic Distance Scale. Additionally, our study will yield a detailed characterization of the extinction law of M33, and a multi- wavelength photometric catalog of great use to the community for studies of stellar populations.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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