An ongoing tidal capture in the Large Magellanic Cloud: the low-mass star cluster KMK88-10 captured by the massive globular cluster NGC 1835?

TL;DR

This study presents evidence suggesting that the small star cluster KMK88-10 in the Large Magellanic Cloud may have been captured by the massive globular cluster NGC 1835, based on deep imaging and structural analysis.

Contribution

It provides the first potential evidence of a tidal capture event of a small star cluster by a massive globular cluster in the LMC.

Findings

KMK88-10 hosts a young stellar population aged 600-1000 Myr.

KMK88-10 shows an elongated structure towards NGC 1835, indicating possible tidal interaction.

A tidal bridge between KMK88-10 and NGC 1835 is suggested by the data.

Abstract

In the context of a project aimed at characterizing the dynamical evolution of old globular clusters in the Large Magellanic Cloud, we have secured deep HST/WFC3 images of the massive cluster NGC 1835. In the field of view of the acquired images, at a projected angular separation of approximately 2 arcmin from the cluster, we detected the small stellar system KMK88-10. The observations provided the deepest color-magnitude diagram ever obtained for this cluster, revealing that it hosts a young stellar population with an age of 600-1000 Myr. The cluster surface brightness profile is nicely reproduced by a King model with a core radius rc = 4 arcsec (0.97 pc), an half-mass radius rhm = 12 arcsec (2.9 pc), and a concentration parameter c~1.3 corresponding to a truncation radius rt~81 arcsec (19.5 pc). We also derived its integrated absolute magnitude (MV=-0.71) and total mass (M~80-160 Msun). The most intriguing feature emerging from this analysis is that KMK88-10 presents a structure elongated in the direction of NGC 1835, with an intracluster over-density that suggests the presence of a tidal bridge between the two systems. If confirmed, this would be the first evidence of a tidal capture of a small star cluster by a massive globular.