Program: GS-2007A-Q-73

Absorption line strengths in unresolved stellar populations are becoming an increasingly popular tool by which to investigate the history of when stars formed in early-type galaxies, including ellipticals, lenticulars and other spheroidal systems. We wish to apply this technique to examine the stellar populations across a complete sample of nearby cD galaxies. Such a systematic study has not yet been undertaken for cD galaxies, which are evolutionarily important objects, thought to be built up through galactic cannibalism. Despite numerous studies of cD galaxies, no high signal-to-noise, high resolution spectroscopic data for the analysis of stellar populations has yet been obtained. The proposed observations are a continuation of an existing program (GS-2006B-Q-71 and GN-2006B-Q-88) which will enable us to measure their spatially resolved line-strengths and, through their interpretation via population modelling, test the star formation histories in cD galaxies as a class. The high efficiency and broad wavelength coverage makes GMOS a highly competitive instrument for building up the stellar population characteristics of a large, statistically significant sample of cD galaxies.