NOAO >   Observing Info >   Approved Programs >   2008B-0090

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Proposal Information for 2008B-0090


PI: Megan Jackson, Lowell Obs. and Georgia State University, mjackson@lowell.edu
Address: Department of Physics and Astronomy, 1400 Mars Hill Rd., Flagstaff, AZ 86001, USA

CoI: Deidre Hunter, Lowell Observatory
CoI: Vera Rubin, Carnegie Institution of Washington--DTM

Title: The Stellar Structure of Dwarf Galaxies

Abstract: In popular models, dwarf galaxies are the product of the Big Bang and the building blocks of giant galaxies. Yet, even the basic structure of dwarf irregular galaxies remains controversial. The \it stellar velocity dispersion, coupled with rotational information, is a diagnostic of how kinematically hot a system is, and, therefore, of its structure. But the stellar velocity dispersion has been measured in only three irregular galaxies so far and inferences from the ratio of rotation speed to velocity dispersion contradict the results of studies of apparent minor-to-major axis ratios. However, these 3 systems are at the high luminosity end of the distribution of dwarfs, near the spiral- dwarf transition. We propose for the first time to push observations of the stellar velocity dispersion to dwarfs of fainter, more typical, luminosity. We were granted time on the KPNO 4-m in semester 2008A. This observing run began the PI's thesis project, and proved that it is possible to obtain the stellar velocity dispersions for our dwarf irregular galaxies. The preliminary results for the stellar velocity dispersion along the major axis of two of our galaxies are included in this proposal. We are now requesting the additional time needed to complete our determination of the structure of dwarf galaxies. Our sample includes 4 dwarf irregular galaxies that span a range of properties; for each of these, we require 4 position angles to unambiguously pin down the inclination and ascertain their structure.


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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