Hints for multiple populations in intermediate-age clusters of the Small Magellanic Cloud

Abstract

We report on the magnitude of the intrinsic [Fe/H] spread in the Small Magellanic Cloud (SMC) intermediate-age massive clusters NGC 339, 361, Lindsay 1 and 113, respectively. In order to measure the cluster metallicity dispersions, we used accurate Stromgren photometry of carefully selected cluster red giant branch (RGB) stars. We determined the Fe-abundance spreads by employing a maximum likelihood approach. The spreads obtained using the more accurate photometry of the brighter RGB stars resulted to be marginal (~ 0.05+-0.03 dex) for NGC 339 and NGC 361, while for Lindsay 1 and Lindsay 113 we obtained metallicity spreads of 0.00+-0.04 dex. From these results, we speculated with the possibility that NGC 361 is added to the group of four SMC clusters with observational evidence of multiple populations (MPs). Furthermore, in the context of the present debate about the existence of Fe-abundance inhomogeneities among old clusters with MPs, these outcomes put new constrains to recent theoretical speculations for making this phenomenon visible.

15 pages, 8 figures. Accepted for publication in The Astronomical Journal

References in corpus (18)

• Multiple Stellar Populations in Globular Clusters
• Age Determination of Six Intermediate-age SMC Star Clusters with HST/ACS
• Concurrent formation of supermassive stars and globular clusters: implications for early self-enrichment
• Iron and s-elements abundance variations in NGC5286: comparison with anomalous globular clusters and Milky Way satellites
• Looking outside the Galaxy: the discovery of chemical anomalies in 3 old Large Magellanic Cloud clusters
• The Search for Multiple Populations in Magellanic Cloud Clusters II: The Detection of Multiple Populations in Three Intermediate-Age SMC Clusters
• Comparing CN and CH Line Strengths in a Homogeneous Spectroscopic Sample of 8 Galactic Globular Clusters
• Stroemgren photometry of Galactic Globular Clusters. I. New Calibrations of the metallicity index
• Evidence for multiple populations in the intermediate age cluster Lindsay 1 in the SMC
• The ability of intermediate-band Stromgren photometry to correctly identify dwarf, subgiant, and giant stars and provide stellar metallicities and surface gravities
• Insights into the chemical composition of the metal-poor Milky Way halo globular cluster NGC 6426
• ESO452-SC11: The lowest mass globular cluster with a potential chemical inhomogeneity
• Kron 3: a fourth intermediate age cluster in the SMC with evidence of multiple populations
• Globular cluster formation with multiple stellar populations: self-enrichment in fractal massive molecular clouds
• A Model for Clumpy Self-Enrichment in Globular Clusters
• The CN-CH positive correlation in the globular cluster NGC 5286
• BS196: an old star cluster far from the SMC main body
• Near-Infrared Photometry of Four Stellar Clusters in the Small Magellanic Cloud

Cited by in corpus (7)

• Metallicities and ages for 35 star clusters and their surrounding fields in the Small Magellanic Cloud
• Metallicities and ages for star clusters and their surrounding fields in the Large Magellanic Cloud
• Metallicity estimates of young clusters in the Magellanic Clouds from Stromgren photometry of supergiant stars
• When does the onset of multiple stellar populations in star clusters occur-II: No evidence of multiple stellar populations in Lindsay 113
• Strömgren metallicities for intermediate-age and old star clusters
• Search for a metallicity spread in the multiple population Large Magellanic Cloud cluster NGC 1978
• Multiple populations of Hbeta emission line stars in the Large Magellanic Cloud cluster NGC1971