We have obtained metal abundances from Washington photometry (C, T1) for a large sample of globular clusters around NGC 3311, the central cD in the Hydra I (A1060) galaxy cluster. Our spatial coverage extends out to a galactocentric radius approximately 2.2 arcmin (about 30 kpc for H₀ = 75). Analysis of the metallicity distribution function (MDF) reveals a median metallicity of (Fe/H)C-T1 = -0.31 with a dispersion of 0.35 dex; the MDF is skewed, with a small but definite low-metallicity tail extending down to (Fe/H)C-T1 approximately -1.8 dex. It may also be bimodal, with significant peaks near (Fe/H)C-T1 = -0.5 and 0.15 dex. We estimate that 30 percent of the clusters exceed solar abundance, based upon a linear extrapolation of the galactic calibrating relation between (c-T(sub1))₀ and (Fe/H)C-T1. Perhaps most notably, the population of clusters near (Fe/H)C-T1 approximately -1 that dominates the MDF in order giant E galaxies is almost totally missing in NGC 3311 making it the most metal-rich system known. Finally, we find a significant radial gradient in mean metallicity, Delta (Fe/H)C-T1/ Delta (log Rgc = -0.78+/-0.60. It is suggested that virtually all the protostellar gas in this cD galaxy went through a considerable amount of pre-enrichment everywhere in the halo, before almost any stars or clusters formed. These data provide a strong challenge to any model which requires low metallicity for globular cluster formation.
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Secker et al. (1995) studied this question.