NOAO >   Observing Info >   Approved Programs >   2006A-0562

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Proposal Information for 2006A-0562


PI: R. Michael Rich, UCLA, rmr@astro.ucla.edu
Address: Division of Astronomy and Astrophysics, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA

CoI: Enrico V. Held, Osservatorio Astronomico Padova
CoI: Luca Rizzi, University of Hawaii
CoI: Ivo Saviane, European Southern Observatory
CoI: Danielle Alloin, CEA
CoI: Fabio Bresolin, University of Hawaii

Title: Near-Infrared Luminosities and Nebular Oxygen Abundances of Dwarf Irregular Galaxies in the M81 group

Abstract: The existence of a luminosity-metallicity (L-Z) relation for dwarf irregular galaxies is still debated (see rationale) partly because the catalogs of abundances are based on inhomogeneous data, luminosities are derived from blue light, and the effect of environment is not considered. Since a few years we've started a modern investigation to obtain oxygen abundances and near-IR luminosities for a sample of dIrr in the three most nearby galaxy groups. Our data for the Sculptor and M81 groups are beginning to shed some light over the controversy, but secure conclusions are undermined by the too few available data for M81 dwarfs. So now we propose to add more evidence by collecting more imaging and spectra of HII regions in the M81 group. With these data: (a) we will derive a homogeneous catalog of abundances; (b) the best measure of total stellar mass, the infrared luminosity will be obtained; (c) the distance uncertainties will be reduced thanks to the stretch in galaxy luminosity which is observed in the near-IR; and (d) the L-Z relation for the M81 group will be compared to that available for the Scl group, thus checking the influence of the environment.


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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