KMHK 1762: Another star cluster in the Large Magellanic Cloud age gap

Abstract

The star cluster (SC) age distribution of the Large Magellanic Cloud (LMC) exhibits a gap from $\sim$ 4 to 10 Gyr ago, with an almost total absence of SCs. Within this age gap, only two confirmed SCs have been identified hitherto. Nonetheless, the star field counterpart does not show the same characteristics, making the LMC a peculiar galaxy where star formation history and cluster formation history appear to differ significantly. We re-analyzed the color-magnitude diagram (CMD) of the KMHK 1762 SC by using the deep optical photometry provided by the "Yes, Magellanic Clouds Again" survey, to robustly assess its age. First, we partially removed foreground and/or field stars by means of parallaxes and proper motions obtained from the {\it Gaia} Early Data Release 3. Then, we applied the Automated Stellar Cluster Analysis package to the cleaned photometric catalogue to identify the isochrone that best matches the CMD of KMHK 1762. The estimated age of KMHK 1762 is $\log (t)=9.74\pm 0.15$ dex ($\sim$5.5 Gyr), that is more than 2 Gyr older than the previous estimation which was obtained with shallower photometry. This value makes KMHK 1762 the third confirmed age gap SC of the LMC. The physical existence of a quiescent period of the LMC SC formation is questioned. We suggest it can be the result of an observational bias, originated by the combination of shallow photometry and limited investigation of the LMC periphery.

6 pages, 4 figures. Accepted for publication in A&A Letter

References in corpus (12)

• Clustering of Local Group distances: publication bias or correlated measurements? I. The Large Magellanic Cloud
• ASteCA - Automated Stellar Cluster Analysis
• The VMC survey -- XLIII. The spatially resolved star formation history across the Large Magellanic Cloud
• Photometry of Magellanic Cloud clusters with the Advanced Camera for Surveys - II. The unique LMC cluster ESO 121-SC03
• STEP: The VST survey of the SMC and the Magellanic Bridge. I. Overview and first results
• Dynamical masses and mass-to-light ratios of resolved massive star clusters -- II. Results for 26 star clusters in the Magellanic Clouds
• Star Clusters in the Magellanic Clouds-1: Parameterisation and Classification of 1072 Clusters in the LMC
• Star cluster formation history along the minor axis of the Large Magellanic Cloud
• The VMC Survey - XII. Star cluster candidates in the Large Magellanic Cloud
• A genuine Large Magellanic Cloud age gap star cluster
• Revisiting newly Large Magellanic Cloud age gap star clusters
• Astrophysical properties of newly discovered Magellanic Cloud star clusters

Cited by in corpus (2)

• Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap
• The YMCA (Yes, Magellanic Clouds Again) survey: probing the outer regions of the Magellanic system with VST