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The Optical Gravitational Lensing Experiment. Ages of about 600 Star Clusters from the LMC

G. Pietrzynski·A. Udalski
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Abstract

We present results of age determination based on the standard procedure of isochrone fitting for about 600 star clusters younger than about 1.2 Gyr from the central parts of the LMC. Comparison of age distributions of star clusters from the LMC and the SMC shows that cluster formation histories are different in these galaxies. The age distribution of the LMC clusters reveals bursty nature of cluster formation in this galaxy, with contrast to the relatively uniform distribution of cluster ages in the SMC. We detected three extended peaks in the distribution of ages of LMC clusters, located at about 7 Myr, 125 Myr and 0.8 Gyr. All detected peaks have complex structure. While the structure of the youngest and the oldest peaks may be spurious due to accuracy of age determination, in the middle peak two evident sub-peaks at 100 Myr and 160 Myr are clearly seen. Similar peaks are seen in the distribution of ages of clusters from the SMC, which indicates that increased cluster formation ratio during these periods might be caused by the last encounter between the Magellanic Clouds. The sample of clusters from the LMC is overabundant in very young (<10 Myr) and old (>400 Myr) clusters, and underabundant in clusters having ages in the range from 80 to 15 Myr with respect to the studied sample of clusters from the SMC.

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G. Pietrzynski, A. Udalski. 2000-10-18. The Optical Gravitational Lensing Experiment. Ages of about 600 Star Clusters from the LMC. https://arxiv.org/abs/astro-ph/0010360

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