NOAO >   Observing Info >   Approved Programs >   2009B-0423

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Proposal Information for 2009B-0423


PI: M. Mouhcine, Liverpool John Moores University,, mm@sastro.livjm.ac.uk
Address: Astrophysics Research Institute, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK

CoI: R. Ibata, Observatoire de Strasbourg
CoI: M. Rejkuba, ESO
CoI: E. Small, Liverpool John Moores University
CoI: D. Bersier, Liverpoo John Moores University

Title: The panoramic view of spiral galaxies: the nature of the outskirts of spirals

Abstract: We propose to use MOSAIC II to undertake a panoramic study of the stellar populations in the outskirts of two spiral galaxies in the Sculptor group, the nearest galaxy group to the Local Group, NGC 253, and NGC 55. These observations will allow accurate measurements of star counts, and color-magnitude diagrams ~ 2 magnitudes below the tip of the red giant branch over one of the largest area so far surveyed to these depths for giant stars in spiral galaxies beyond the Local Group. As such, this survey will provide the missing link between studies of the Local Group spirals with those beyond, and to establish whether the findings made in the outskirts the Local Group spirals are representative of other galaxies. We will measure metallicity distribution functions and stellar density profiles from star counts down to very low surface brightnesses, equivalent to ~ 31 magnitudes per square arcsec. These observations will allow the most detailed comparative studies to date of (i) the structural properties and the spatial variation of the metallicity distributions of halo stars, (ii) properties of galactic disks, and (iii) the most complete study of globular cluster systems around spirals, and how they connect to field stars. The panoramic view will allow for a meaningful search of tidal streams and merging debris around spirals. These observations will offer the ideal set to verify the predictions of galaxy formation models.


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