NGC 6357 is an active star-forming region located in the Sagittarius arm
displaying several star clusters, which makes it a very interesting target to
investigate star formation and early cluster evolution. We explore NGC 6357
with the "VISTA Variables in the V\'ia a L\'actea" (VVV) photometry of seven
embedded clusters (ECs), and one open cluster (OC) projected in the outskirts
of the complex.Photometric and structural properties (age, reddening, distance,
core and total radii) of the star clusters are derived. VVV saturated stars are
replaced by their 2MASS counterparts. Field-decontaminated VVV photometry is
used to analyse Colour-Magnitude Diagrams (CMDs), stellar radial density
profiles (RDPs) and determine astrophysical parameters. We report the discovery
of four ECs and one intermediate-age cluster in the complex area. We derive a
revised distance estimate for NGC 6357 of 1.78±0.1 kpc based on the cluster
CMD morphologies. Among the ECs, one contains the binary star the WR 93, while
the remaining ones are dominated by pre-main sequence (PMS) stars,
young-stellar objects (YSO) and/or and have a developed main sequence. These
features reflect a significant age spread among the clusters. Evidence is found
that the relatively populous cluster Pismis 24 hosts two subclusters.Comment: This article will be published in the A&A. 11 pages, 15 figures and 3
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