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6. Luminosity function

The cluster luminosity function in terms of number of members in intervals of 0.5 mag width in absolute magnitude Mv is shown in Fig. 10 (click here) (full histogram). For comparison, the normalized luminosity functions of NGC2335 (dashed histogram) and NGC2343 (dotted histogram), as taken from Clariá (1973) and Clariá (1972), respectively, and that calculated by Taff (1974) (dashed line) from data of 62 well-studied open clusters, are also shown in Fig. 10 (click here).

Figure 10: Luminosity function of NGC2323 (full histogram), compared to the normalized histograms of NGC2335 (dashed histogram) and NGC2343 (dotted histogram), and the Taff (1974) luminosity function (dashed line)

Three important features should be noticed: (1) the number of stars per bin in NGC2323 reaches its maximum and begins to decrease near Mv=2.0. The maximum lies between the peaks of the histograms of NGC2335 and NGC2343. These two clusters aged 150 Myr and 110 Myr respectively (Clariá 1972, 1973) are located in the direction of CMa OB1 at nearly the same distance as NGC2323. The turnover in the distribution for tex2html_wrap_inline1600 is probably real since our cluster survey ceases to be complete for stars beyond a limiting magnitude of about V=13.5, corresponding to Mv=2.9. (2) Although the cluster histograms and the Taff luminosity function show in general a good agreement, the slope of the luminosity function in NGC2323 appears to be somewhat steeper than in the Taff's function. (3) The three clusters lack stars brighter than Mv=-2.0.

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