Photographic photometry of 20 star clusters and their
adjoining fields has been carried out to determine the
colour magnitude diagram for stellar systems in the Small
Magellanic Cloud, using plates from the U.K. 1.2m Schmidt
telescope. The W-N-E periphery of the Cloud has been
The main difficulty of the SMC star clusters is the
contamination of cluster members by stars in the surrounding
The evolutionary history of the star clusters seems to
be similar to that of the surrounding field, implying that
the background halo of the SMC is not well mixed.
Old clusters have been found over the whole Cloud
exhibiting differences in the morphology of the H-B which
in most cases is very well populated at the red side of
the RR Lyrae stars strip.
Two more characteristics are i) the existence of very
red stars (in three cases they are proved carbon stars) and
ii) the large number of blue faint stars.
The metallicity has been shown to be low in the SMC
but the characteristics found in the old clusters are
those normally found in intermediate age clusters of our
Galaxy. Thus the age of the western halo clusters is
~10⁹ - 5 x 10⁹ yrs, whereas the northern halo clusters
are even younger.
The second group of clusters comprises young clusters
which occupy the north part of the SMC or the north-east
arm, since no young objects have been detected at the
western part of this galaxy.
The colour magnitude diagrams of the clusters and
the adjoining field of the north-west arm give an age
estimate of this feature of about 5 x 10⁷ yrs.
The other small young clusters in the northern side
of the Cloud are objects of the SMC disc and their ages
are 10⁶ - 10⁷ years.