NOAO >   Observing Info >   Approved Programs >   2008A-0085

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Proposal Information for 2008A-0085


PI: Megan Jackson, Georgia State University, mjackson@phy-astr.gsu.edu
Address: Dept of Physics & Astronomy, 29 Peachtree Center Ave, Science Annex, Suite 400, Atlanta, GA 30303-4106, 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. Furthermore, our sample of four galaxies covers a range of luminosities in order to address the question of whether the physical structure of dwarfs changes as one goes to smaller (less luminous) systems. In addition we will use these data to determine the disk and halo dark matter content in galaxies where the dark matter content is estimated to be anywhere from 0 to ~10 times that of the luminous matter.


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