Studies during the last decade have revealed that nearly all globular clusters (GCs) host multiple populations (MPs) of stars with a distinctive chemical patterns in light elements. No evidence of such MPs has been found so far in lower mass (<~ 104 M⊙) open clusters nor in intermediate-age (1-2 Gyr) massive (>105 M⊙) clusters in the Local Group. Young massive clusters (YMCs) have masses and densities similar to those expected of young GCs in the early Universe, and their near-infrared spectra are dominated by the light of red super giants (RSGs). The spectra of these stars may be used to determine the cluster's abundances, even though the individual stars cannot be spatially resolved from one another. We carry out a differential analysis between the Al lines of YMC NGC 1705: 1 and field Small Magellanic Cloud RSGs with similar metallicities. We exclude at high confidence extreme [Al/Fe] enhancements similar to those observed in GCs like NGC 2808 or NGC 6752. However, smaller variations cannot be excluded.
Cabrera-Ziri I., Lardo C., Davies B., Bastian N., Beccari G., Larsen S.S., et al. (2016). Searching for GC-like abundance patterns in young massive clusters. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 460(2), 1869-1875 [10.1093/mnras/stw1090].
Searching for GC-like abundance patterns in young massive clusters
Lardo C.Membro del Collaboration Group
;
2016
Abstract
Studies during the last decade have revealed that nearly all globular clusters (GCs) host multiple populations (MPs) of stars with a distinctive chemical patterns in light elements. No evidence of such MPs has been found so far in lower mass (<~ 104 M⊙) open clusters nor in intermediate-age (1-2 Gyr) massive (>105 M⊙) clusters in the Local Group. Young massive clusters (YMCs) have masses and densities similar to those expected of young GCs in the early Universe, and their near-infrared spectra are dominated by the light of red super giants (RSGs). The spectra of these stars may be used to determine the cluster's abundances, even though the individual stars cannot be spatially resolved from one another. We carry out a differential analysis between the Al lines of YMC NGC 1705: 1 and field Small Magellanic Cloud RSGs with similar metallicities. We exclude at high confidence extreme [Al/Fe] enhancements similar to those observed in GCs like NGC 2808 or NGC 6752. However, smaller variations cannot be excluded.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
