NOAO >   Observing Info >   Approved Programs >   2011A-0116

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Proposal Information for 2011A-0116


PI: Megan Jackson, Lowell Observatory, mjackson@lowell.edu
Address: 1400 W. Mars Hill Rd., Flagstaff, AZ 86001, USA

CoI: Deidre Hunter, Lowell Observatory
CoI: Vera Rubin, Carnegie Institution of Washington-DTM
CoI: Se-Heon Oh, University of Cape Town

Title: The Stellar Kinematics of Dwarf Irregular Galaxy DDO 125: Is this a galaxy without dark matter?

Abstract: DDO 125 may contain little or no dark matter, according to some radio observations of the neutral hydrogen gas in the disk. However, no dark matter could be the result of assuming a maximum stellar disk but, we can find out about the real stellar disk from kinematics of the stars. If a turnover in the rotation of the stars is detected and the rotation of the stars is flat after the turnover point, then dark matter would be needed to explain the stellar rotation curve of DDO 125. If there is, in fact, no turnover point and the stars and the gas follow each other kinematically, then there may be little or no dark matter detectable in this system. This could indicate a different evolutionary history. There are recent studies that show stars and gas do not move in the same way, thus, it could be quite possible that the stars and the gas of DDO 125 do not follow each other. Therefore, we propose to use the KPNO 4-m+Echelle as a 3\arcmin longslit spectrograph to obtain the stellar kinematics of DDO 125. We will use a cross-correlation function to determine heliocentric radial velocities and velocity dispersions as a function of radius for the stellar disk of DDO 125 and compare these to the gas kinematics determined from newly acquired 21 cm VLA HI data.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2011A-0116

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