NOAO >   Observing Info >   Approved Programs >   2004B-0005

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Proposal Information for 2004B-0005


PI: Deidre Hunter, Lowell Observatory, dah@lowell.edu
Address: 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA

Title: The Stellar Edges of Irregular Galaxies

Abstract: There is considerable interest in, and ignorance of, the outer parts of galaxies. Galactic outer edges are the interaction zone between galactic and intergalactic material and are also most sensitive to galaxy-galaxy interactions. Dwarf Im galaxies, in particular, may be particularly sensitive to their external environment. In one Im system that I observed to (mu)_V=29 mag/arcsec^2 there were several surprises: 1) The starlight continues without an edge as far as the measurements extend, contrary to predictions of several models, 2) The radial surface brightness profile changes slope for no apparent reason, and 3) the color remains constant throughout the galaxy, implying the same star formation history even to the outer parts. I want to see if these unusual features are found in other Im systems. Therefore, I am proposing to continue my exploration of the stellar populations in the outer parts of nearby Im galaxies through very deep B imaging of a galaxy for which I got deep V imaging last year. These data will be used to determine the star formation history at the edges of irregular galaxies.


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