Open AccessYoung star clusters immersed in intermediate‐age fields in the Small Magellanic Cloud
Author(s) -
Piatti Andrés E.,
Sarajedini Ata,
Geisler Doug,
Clark David,
Seguel Juan
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.11604.x
Subject(s) - physics , astrophysics , globular cluster , metallicity , stars , photometry (optics) , small magellanic cloud , star cluster , astronomy , red giant branch , red clump , large magellanic cloud , hubble sequence , horizontal branch , open cluster , red giant , star formation , advanced camera for surveys , spiral galaxy
We present CCD photometry in the Washington C and T 1 filters for six star clusters (B 34, NGC 256, NGC 265, NGC 294, IC 1611 and NGC 376) in the Small Magellanic Cloud (SMC) and their surrounding fields. The resultant colour–magnitude diagrams (CMDs) extend from T 1 ∼ 14 to as faint as T 1 ∼ 22 revealing the main‐sequence turnoffs of the clusters. Adopting a metallicity of Z = 0.004 , we compare our cluster photometry with theoretical isochrones in the Washington system in order to derive ages. To facilitate age determination of the surrounding fields, we use the magnitude difference between the helium‐burning red clump stars and the main‐sequence turnoff. Finally, we estimate mean metallicities for the field stars by comparing the location of the field red giant branch with standard giant branches for Galactic globular clusters of known abundance, corrected for age effects. Combining these results with our previous work, we find a clear trend of younger clusters being located closer to the centre of the SMC. In addition, there is a tendency for the mean metallicity and its dispersion to be greater inside 4° of the SMC's centre as compared to outside this radius. As far as the properties of the field stars are concerned, we find little correlation between the ages of the clusters and those of the field stars against which they are projected. Clearly, more work needs to be done to clarify these trends.