NOAO >   Observing Info >   Approved Programs >   2010B-0003

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Proposal Information for 2010B-0003


PI: Robert E. Wilson, University of Florida, wilson@astro.ufl.edu
Address: Department of Astronomy, PO Box 112055, 211 Bryant Space Science Center, Gainesville, FL, 32611-2055, USA

CoI: Walter van Hamme, Department of Physics, Florida International University
CoI: Francesc Vilardell, Universitat d'Alacant

Title: The extinction and the distance to the Andromeda Galaxy

Abstract: The Andromeda Galaxy (M31) is potentially one of the best calibrators for the Cosmic Distance Scale, and thus for determining the age and evolution of the Universe. Currently, the distance to M31 is known with an uncertainty below 5% that includes most of the systematics. Although the distance determination is precise, the uncertainty could be largely reduced by means of photometry in the infrared, where interstellar extinction is low, and by accurate determination of extinction in M31. The distance uncertainty can be reduced by up to a factor of two, deriving the most precise extragalactic distance determination ever obtained. We request Gemini-North NIRI photometry to determine the spectral energy distributions (SED) of two M31 EBs that have been selected as optimal distance indicators from existing high-precision B,V light curves. In addition, the observed SED, compared with the intrinsic SED, will provide the first extinction law for M31 at infrared wavelengths.


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