The kinematics of Small Magellanic Cloud star clusters

AbstractTo study the evolution of binary star clusters, we have imaged seven systems in the Small Magellanic Cloud with the SOAR 4m telescope using B and V filters. The sample contains pairs with well-separated components (d < 30 pc) as well as systems that apparently have merged, as evidenced by their unusual structures. By employing isochrone fitting to their color–magnitude diagrams, we have determined reddening values, ages and metallicities, and by fitting King models to their radial stellar-density profiles we estimated core radii. Disturbances of the density profiles are interpreted as evidence of interactions. Properties such as the distances between their components and their age differences are addressed in terms of the timescales involved, to assess the physical connection of the system. In two cases, the age difference is more than 50 Myr, which suggests a chance alignment, capture or sequential star formation.

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The Oldest Star Clusters in the Small Magellanic Cloud

Symposium - International Astronomical Union ◽

10.1017/s0074180900118510 ◽

1999 ◽

Vol 190 ◽

pp. 445-445 ◽

Cited By ~ 1

Author(s):

Kenneth J. Mighell ◽

Ata Sarajedini ◽

Rica S. French

Keyword(s):

Star Formation ◽

Theoretical Model ◽

Observational Data ◽

Hubble Space Telescope ◽

Star Clusters ◽

Magellanic Cloud ◽

Wide Field ◽

Small Magellanic Cloud ◽

Formation Model ◽

Age Sequence

We present our analysis of archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) observations in F450W (~B) and F555W (~V) of the intermediate-age populous star clusters NGC 121, NGC 339, NGC 361, NGC 416, and Kron 3 in the Small Magellanic Cloud. We use published photometry of two other SMC populous star clusters, Lindsay 1 and Lindsay 113, to investigate the age sequence of these seven star clusters in order to improve our understanding of the formation chronology of the SMC. We analyzed the V vs B–V and MV vs (B–V)o color-magnitude diagrams of these populous Small Magellanic Cloud star clusters using a variety of techniques and determined their ages, metallicities, and reddenings. These new data enable us to improve the age-metallicity relation of star clusters in the Small Magellanic Cloud. In particular, we find that a closed-box continuous star-formation model does not reproduce the age-metallicity relation adequately. However, a theoretical model punctuated by bursts of star formation is in better agreement with the observational data. The full details of this analysis are reported in Mighell, Sarajedini, & French (1998, AJ, 116, 2395).

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Star clusters in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900200259 ◽

1991 ◽

Vol 148 ◽

pp. 161-164 ◽

Cited By ~ 1

Author(s):

S. van den Bergh

Keyword(s):

Cluster Formation ◽

Star Clusters ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Open Clusters ◽

Small Magellanic Cloud ◽

Cloud Clusters ◽

The Galaxy

Star clusters in the Magellanic Clouds (MCs) differ from those in the Galaxy in a number of respects: (1) the Clouds contain a class of populous open clusters that has no Galactic counterpart; (2) Cloud clusters have systematically larger radii rh than those in the Galaxy; (3) clusters of all ages in the Clouds are, on average, more flattened than those in the Galaxy. In the Large Magellanic Cloud (LMC) there appear to have been two distinct epochs of cluster formation. LMC globulars have ages of 12-15 Gyr, whereas most populous open clusters have ages <5 Gyr. No such dichotomy is observed for clusters in the Small Magellanic Cloud (SMC) The fact that the SMC exhibits no enhanced cluster formation at times of bursts of cluster formation in the LMC, militates against encounters between the Clouds as a cause for enhanced rates of star and cluster formation.

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