scholarly journals Washington photometry of five star clusters in the Large Magellanic Cloud

2009 ◽  
Vol 5 (S266) ◽  
pp. 500-503
Author(s):  
Andrés E. Piatti ◽  
Doug Geisler ◽  
Ata Sarajedini ◽  
Carme Gallart
Keyword(s):  
Detailed Analysis ◽  
Cluster Formation ◽  
Star Clusters ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Ccd Photometry ◽  
Outer Disk ◽  
Field Star ◽  
Show Evidence

AbstractWe 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.

scholarly journals Star clusters in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 161-164 ◽  
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.

scholarly journals Star clusters in the Magellanic Clouds

2018 ◽  
Vol 616 ◽  
pp. A187 ◽  
Author(s):  
P. K. Nayak ◽  
A. Subramaniam ◽  
S. Choudhury ◽  
Ram Sagar
Keyword(s):  
Gravitational Lensing ◽  
Cluster Formation ◽  
Age Distribution ◽  
Star Clusters ◽  
Temporal Distribution ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Photometric Data ◽  
Spatio Temporal ◽  
Online Catalogue

Aims. We aim to estimate the age and reddening parameters of already identified star clusters within the Small Magellanic Cloud (SMC) in a consistent way using available photometric data, classify them based on their mass and strength, and study their spatiotemporal distribution. Methods. We have used a semi-automated quantitative method, developed in the first paper of this series (Paper I), to estimate the cluster parameters using the V and I band photometric data from the Optical Gravitational Lensing Experiment (OGLE) III survey. Results. We estimated parameters of 179 star clusters (17 are newly parameterised) and classified them into four groups. We present an online catalogue of parameters as well as cleaned and isochrone-fitted colour magnitude diagrams of 179 clusters. We compiled age information of 468 clusters by combining previous studies with our catalogue, to study their spatio-temporal distribution. Most of the clusters located in the southern part of the SMC are in the age range 600 Myr–1.25 Gyr, whereas, the clusters younger than 100 Myr are mostly found in the northern SMC, with the central SMC showing continuous cluster formation. The peak of the cluster age distribution is identified at 130 ± 35 Myr, very similar to the Large Magellanic Cloud (LMC) in Paper I. Conclusions. We suggest that the burst of cluster formation at 130 Myr is due to the most recent LMC-SMC interaction. 90% of the studied sample is found to have mass < 1700 M⊙, suggesting that the SMC is dominated by low mass clusters. There is tentative evidence for compact clusters in the LMC when compared to those in the Galaxy and the SMC. A progressive shifting of cluster location from the south to north of the SMC is identified in last ~600 Myr. The details of spatio-temporal distribution of clusters presented in two videos as part of this study can be used as a tool to constrain details of the recent LMC-SMC interactions.

scholarly journals Ages and Metallicities of Star Clusters and Surrounding Fields in the Outer Disk of the Large Magellanic Cloud

1998 ◽  
Vol 116 (2) ◽  
pp. 723-737 ◽  
Author(s):  
Eduardo Bica ◽  
Doug Geisler ◽  
Horacio Dottori ◽  
Juan J. Clariá ◽  
Andrés E. Piatti ◽  
...  
Keyword(s):  
Star Clusters ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Outer Disk

scholarly journals CCD SDSS gr Photometry of Poorly Studied Star Clusters in the Large Magellanic Cloud

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Andrés E. Piatti
Keyword(s):  
Metal Content ◽  
Star Clusters ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Main Body ◽  
Field Star ◽  
Subtraction Procedure ◽  
Radial Profiles ◽  
First Time ◽  
Stellar Density

We present for the first time CCD SDSS gr photometry, obtained at the Gemini South telescope with the GMOS attached, of stars in the field of the poorly studied star clusters NGC1768, HS 85, SL 676, NGC2107, NGC2190, and SL 866, which are distributed in the main body of the Large Magellanic Cloud. We applied a subtraction procedure to statistically clean the cluster CMDs from field star contamination. In order to disentangle cluster features from those belonging to their surrounding fields, we applied a subtraction procedure which makes use of variable cells to reproduce the field star color-magnitude diagrams (CMDs) as closely as possible. We then traced their stellar density radial profiles from star counts performed over the cleaned field stars dataset and derived their radii. Using the cleaned cluster CMDs, we estimated ages and metallicities from matching theoretical isochrones computed for the SDSS system. The studied star clusters have ages from 0.1 up to 2.0 Gyr and are of slightly metal-poor metal content ([Fe/H]≈−0.4 dex).

Statistics of Stellar Populations of Star Clusters and Surrounding Fields in the Outer Disk of the Large Magellanic Cloud

1999 ◽  
Vol 117 (6) ◽  
pp. 2841-2855 ◽  
Author(s):  
João F. C. Santos, Jr. ◽  
Andrés E. Piatti ◽  
Juan J. Clariá ◽  
Eduardo Bica ◽  
Doug Geisler ◽  
...  
Keyword(s):  
Star Clusters ◽  
Stellar Populations ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Outer Disk

scholarly journals Metal abundances of Magellanic Cloud clusters

1991 ◽  
Vol 148 ◽  
pp. 341-342
Author(s):  
D. Geisler ◽  
A. McWilliam ◽  
N. Suntzeff ◽  
M. Mateo ◽  
J. Graham ◽  
...  
Keyword(s):  
Main Sequence ◽  
Star Clusters ◽  
Large Magellanic Cloud ◽  
Small Sample ◽  
Magellanic Cloud ◽  
High Dispersion ◽  
Ccd Photometry ◽  
Elemental Abundances ◽  
Cloud Clusters ◽  
Metal Abundances

We have obtained Washington CCD photometry with the CTIO 4m and 1.5m for ˜50 intermediate-to-old age star clusters in the Clouds. The data extend to near or below the main sequence and provide excellent photometry for the giants, from which precise (internal errors <0.1 dex) mean cluster abundances can be determined. We present data for several of the clusters and discuss the results. Intermediate resolution spectra have also been obtained for some 16 clusters with the CTIO 4m ARGUS multiple-object fibre-fed spectrograph. Finally, we have also obtained high dispersion (R˜20,000) échelle spectra for several of the brighter giants in a small sample of Large Magellanic Cloud (LMC) clusters. Detailed elemental abundances derived from these spectra will be presented. These data will help refine our knowledge of the age-metallicity relation in the Clouds.

Star clusters of the Large Magellanic Cloud - CCD photometry of NGC 1831

1992 ◽  
Vol 104 ◽  
pp. 1100 ◽  
Author(s):  
A. Vallenari ◽  
C. Chiosi ◽  
G. Bertelli ◽  
G. Meylan ◽  
S. Ortolani
Keyword(s):  
Star Clusters ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Ccd Photometry

scholarly journals The age distribution function of star clusters in the LMC

1991 ◽  
Vol 148 ◽  
pp. 193-194
Author(s):  
M. Alongi ◽  
C. Chiosi
Keyword(s):  
Distribution Function ◽  
Cluster Formation ◽  
Age Distribution ◽  
Star Clusters ◽  
Bimodal Distribution ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Combined Effect ◽  
Sole Agent ◽  
Age Gap

We present the age distribution function for Large Magellanic Cloud (LMC) clusters obtained from a relationship between their integrated U BV colours and age. We discuss further the results by Chiosi et al. (1988) on the nature of the bimodal distribution of the (B - V) colours for LMC clusters. Their conclusion that bimodality in the colour stems from the combined effect of the age distribution function and the rate at which clusters change colour with age, is revisited. The result of our analysis shows that the age distribution is the sole agent and that a real age gap is present. Finally, we draw some conclusions about the efficiency of cluster formation and disruption in the LMC.

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