Bibcode
Piatti, Andrés E.; Geisler, Doug; Sarajedini, Ata; Gallart, C.
Bibliographical reference
Star clusters: basic galactic building blocks throughout time and space, Proceedings of the International Astronomical Union, IAU Symposium, Volume 266, p. 500-503
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1
2010
Citations
0
Refereed citations
0
Description
We present CCD photometry in the Washington-system C and T1
passbands down to T1 ~ 22.5 mag in the fields of NGC 1697, SL
133, NGC 1997, SL 663, and OHSC 28, five mostly unstudied star clusters
in the LMC. Cluster radii were estimated from star counts in
appropriately sized boxes distributed throughout the entire observed
fields. We perform a detailed analysis of field-star contamination and
derive cluster colour-magnitude diagrams (CMDs). Based on the best fits
of isochrones computed by the Padova group to the (C - T1,
T1) CMDs, the δ(T1) index and the
‘standard giant-branch’ procedure, we derive metallicities
and ages for the five clusters. With the exception of NGC 1697 (age =
0.7 Gyr, [Fe/H] = 0.0 dex), the remaining four clusters are of
intermediate age (from 2.2 to 3.0 Gyr) and relatively metal poor ([Fe/H]
= -0.7 dex). We combine our sample with clusters with ages and
metallicities on a similar scale and examine relationships between
position in the LMC, age and metallicity. We confirm previous results
that clusters younger than ~ 1 Gyr were formed during an outside-in
process; this occurred after a burst of cluster formation that took
place mainly in the outer disk and peaked ~ 2 Gyr ago. Finally, the
cluster and field age-metallicity relations (AMRs) show evidence for a
metallicity offset but do overlap, particularly on the upper-envelope
side of the cluster AMR.