NOAO >   Observing Info >   Approved Programs >   2011B-0057

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Proposal Information for 2011B-0057


PI: Letizia Stanghellini, NOAO, lstanghellini@noao.edu
Address: PO Box 26732, 950 North Cherry Avenue, Tucson, AZ 85726-6732, USA

CoI: Laura Magrini, INAF, Arcetri Observatory
CoI: Eva Villaver, Universidad Autonoma Madrid
CoI: Viviana Casasola, INAF, IRA, Bologna
CoI: Daniele Galli, INAF, Arcetri Observatory

Title: The HII region population in M81 and the evolution of the radial metallicity gradient

Abstract: We propose to acquire medium resolution spectroscopy of HII regions in the spiral galaxy M81 to determine the alpha-element metallicity of the young populations across the galaxy disk. Planetary nebulae in M81 have been already studied spectroscopically, yielding to a radial metallicity gradient which is steeper that those found in the Galaxy and in M33. While previous studies have yielded the alpha-element metallicity of a few HII regions, a radially significant coverage of this galaxy is still lacking. With the proposed observations we plan to determine detailed plasma diagnostics and O, N, Ne, Ar, S, and He abundances for targets whose spatial distribution is ideally suited for gradient analysis. We plan to study the nature of the HII region population in M81 and, together with the PN data available, to derive the alpha-element gradient at two epochs (thus its evolution). The results will constitute essential constraints to galaxy evolutionary models. Furthermore, we will compare these results with those of other galaxies to study mass and metallicity effects on radial gradients and chemical enrichment.


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



NOAO >   Observing Info >   Approved Programs >   2011B-0057

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