NOAO >   Observing Info >   Approved Programs >   2008B-0060

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Proposal Information for 2008B-0060


PI: William C. Keel, University of Alabama, keel@bildad.astr.ua.edu
Address: Physics Department, Box 870324, Tuscaloosa, AL 35487, USA

CoI: Anna Manning, University of Alabama
CoI: Chris Lintott, Oxford University
CoI: Benne Holwerda, STScI

Title: Backlit galaxies by the hundreds: new steps toward the evolution of dust

Abstract: Photometric analysis of backlit galaxies is a powerful way to measure the extinction in disks, but has hitherto been limited by the number of suitable pairs near enough for analysis. New searches of the SDSS imagery (mostly from the public galaxyzoo.org project) have revealed hundreds of candidate pairs, opening the possibility of tracing extinction properties across Hubble type and surface brightness, and using spiral/spiral pairs to extend extinction measures into the UV through incorporating GALEX survey data. These is a necessary step toward adding silhouetted galaxies in deep HST imagery to trace the cosmic evolution of dust in galaxies with a single technique. Our analysis so far shows that the SDSS data are excellent for finding these pairs, but that deeper imagery is needed for the requisite extinction measurements. Better knowledge of internal extinction enters into, for example, the accuracy of SN Ia luminosity measures, star-formation rates, and the fraction of galaxies with bars.


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NOAO >   Observing Info >   Approved Programs >   2008B-0060

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