B-R colours of globular clusters in NGC 6166 (A2199)
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abstract
We have analysed new R-band photometry of globular clusters in NGC 6166, the
cD galaxy in the cooling flow cluster A2199. In combination with the earlier B
photometry of Pritchet \& Harris (1990), we obtain B$-$R colours for $\sim$ 40
globular clusters in NGC 6166. The mean B$-$R is 1.26 $\pm$ 0.11, corresponding
to a mean [Fe/H] = $-$1 $\pm$ 0.4. Given that NGC 6166 is one of the most
luminous cD galaxies studied to date, our result implies significant scatter in
the relationship between mean cluster [Fe/H] and parent galaxy luminosity. We
obtain a globular cluster specific frequency of S$_N$ $\sim$ 9, with a possible
range between 5 and 18. This value is inconsistent with the value of S$_N$
$\leq$ 4 determined earlier by Pritchet \& Harris (1990) from B-band
photometry, and we discuss possible reasons for the discrepancy. Finally, we
reassess whether or not cooling flows are an important mechanism for forming
globular clusters in gE/cD galaxies.
