A genuine Large Magellanic Cloud age gap star cluster

Abstract

ABSTRACT We confirm the existence of a second Large Magellanic Cloud (LMC) star cluster, KMHK 1592, with an age that falls in the middle of the so-called LMC star cluster age gap, a long period of time (∼4–11 Gyr) where no star cluster had been uncovered, except ESO 121-SC 03. The age (8.0 ± 0.5 Gyr) and the metallicity ([Fe/H] = −1.0 ± 0.2 dex) of KMHK 1592 were derived from the fit of theoretical isochrones to the intrinsic star cluster colour–magnitude diagram sequences, which were unveiled using a robust star-by-star membership probability procedure. Because of the relative low brightness of the star cluster, deep GEMINI GMOS images were used. We discuss the pros and cons of three glimpsed scenarios that could explain the presence of both LMC age gap star clusters in the outskirts of the LMC, namely: in situ star cluster formation, capture from the Small Magellanic Cloud, or accretion of a small dwarf galaxy.