|Título||Probing embedded star clusters in the HII complex NGC6357 with VVV
Lima, Eliade Ferreira
Bica, Eduardo Luiz Damiani
Bonatto, Charles Jose
Saito, Roberto K.
|Abstract||Context. NGC6357 is an active star-forming region located in the Sagittarius arm that displays several star clusters, which makes it a very interesting target to investigate star formation and early cluster evolution. Aims. We explore NGC6357 with the VISTA Variables in the Vía Láctea (VVV) photometry of seven embedded clusters (ECs), and one open cluster projected in the outskirts of the complex. Methods. Photometric and structural properties (age, reddening, distance, core, and total radii) of the star clusters were derived. VVV saturated stars were replaced by their 2MASS counterparts. Field-decontaminated VVV photometry was used to analyse colour– magnitude diagrams (CMDs) and stellar radial density profiles and determine astrophysical parameters. Results. We report the discovery of four ECs and one intermediate-age cluster in the complex area. We derive a revised distance estimate for NGC6357 of 1.78 ± 0.1 kpc based on the cluster CMD morphologies. Of the ECs, one contains the binary star WR93, while the remaining ones are dominated by pre-main sequence stars, young stellar objects, 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.
|Contido em||Astronomy and astrophysics. Les Ulis. Vol. 568 (Aug. 2014), A16, 11 p.
Formacao de estrelas
[en] Instrumentation: adaptive optics
[en] Open clusters and associations: general
[en] Open clusters and associations: individual: NGC6357
|Tipo||Artigo de periódico
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