NOAO >   Observing Info >   Approved Programs >   2010A-0109

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Proposal Information for 2010A-0109


PI: Fabio Bresolin, University of Hawaii, bresolin@ifa.hawaii.edu
Address: Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA

CoI: Robert C. Kennicutt, Cambridge University, UK

Title: Testing for azimuthal abundance gradients in spiral galaxies: M101

Abstract: While galactocentric \em radial abundance gradients in spiral galaxies have been studied for a long time, virtually nothing is known about the existence of \em azimuthal variations of the present-day metallicity. Theory predicts a very small (<0.05 dex) effect, but very few observations of extragalactic \hii regions and Galactic stars suggest otherwise, with changes up to 0.3 dex over distances of a few kpc. Using the most accurate \hii region abundance diagnostics, based on the detection of the \oiii\lin4363 auroral line, it is possible to test for the presence of azimuthal gradients in spiral disks. This has natural implications for models of the chemical evolution of galaxies, which currently assume instantaneous recycling of stellar-processed material ejected by winds and SN explosions, and to verify the impact of accretion on the chemical evolution of disks. The grand-design spiral galaxy M101, with its well studied radial abundance gradient extending over a factor of 10 in O/H, and the likely accretion of cold gas from its surroundings, is well suited for this test.


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