A new Extended Main Sequence Turnoff star cluster in the Large Magellanic Cloud

Abstract

We present results on the age and metallicity estimates of the poorly studied Large Magellanic Cloud (LMC) cluster SL 529, from CCD SDSS gr photometry obtained at the Gemini South telescope with the GMOS attached. The cluster main-sequence turnoffs (MSTO) region possesses an extended structure, with an age spread (~0.5 Gyr) bigger than the mean age width of known extended MSTO (EMSTO) LMC clusters. We report for the first time a mean cluster age of 2.25 Gyr and a mean cluster metallicity of Z = 0.004, which place it as the most metal-poor and oldest cluster in the EMSTO LMC cluster group. In addition, the cluster red clump appears to be formed by two concentrations of stars - although it is not clear whether this feature can be caused, in part, by binary interactions and mergers - whereas the cluster core radius of 4.2 pc is in excellent agreement with those determined for the previously 12 known EMSTO LMC clusters.