NOAO >   Observing Info >   Approved Programs >   2006A-0017

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Proposal Information for 2006A-0017


PI: William Harris, McMaster University, harris@physics.mcmaster.ca
Address: Physics Department, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada

CoI: Kristin Woodley, McMaster University
CoI: Gretchen Harris, University of Waterloo
CoI: Doug Geisler, Universidad de Concepcion
CoI: Matias Gomez, Universidad de Concepcion

Title: Dynamics, Metallicity, and Age Distribution of the Globular Cluster System of NGC 5128

Abstract: We propose to use the CTIO 4m + Hydra to study the system of globular clusters (GCs) in NGC 5128 (Centaurus A), the nearest giant elliptical galaxy. First, we will use long exposures to obtain integrated spectra at very high signal-to-noise for the 100 brightest known GCs in the galaxy. From Lick/IDS spectral indices, we will simultaneously determine cluster metallicity, [(alpha)/Fe], and relative age, at higher precision and with a larger GC sample than has been done for other galaxies. Our results will make a major step towards building the GC \sl age distribution function (ADF) - a crucial element in reconstructing the formation history of this unique galaxy through mergers and starbursts, but one which is only beginning to be uncovered. Second, we will measure radial velocities for 120 newly identified GC candidates. When combined with previous GC velocity data in the literature, this will allow a comprehensive dynamical study with a `pure' sample of more than 450 GCs. We will investigate the GC system kinematics and dynamics versus metallicity and radius; search for velocity-defined and metallicity-defined merger subgroups; and define the GC metallicity distribution from a cluster sample twice as large as in any previous study. This project has previously been awarded time in 2005A, but we were able to achieve only ~eq 30% of our goals due to weather and instrument problems.


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