2016ApJ...820..119K

We report the discovery of an ultra-faint star cluster in the constellation of Centaurus. This new stellar system, Kim 3, features a half-light radius of r_h = 2.29_–0.52^+1.28 pc and a total luminosity of M_V= +0.7±0.3. Approximately 26 stars are identified as candidate member stars down to four magnitudes below the main-sequence turn-off, which makes Kim 3 the least luminous star cluster known to date. The compact physical size and extreme low luminosity place it close to faint star clusters in the size-luminosity plane. The stellar population of Kim 3 appears to be relatively young (9.5_–1.7^+3.0 Gyr) and metal-poor ([Fe/H] -1.6_–0.30^+0.45) at a heliocentric distance of 15.14_–0.28^+1.00 kpc. The cluster lacks a well-defined center, and a small but prominent group of stars consistent with the Kim 3 isochrone is present approximately 9.7 pc in projection south of the cluster center. Both are signs of the cluster being in the final stage of tidal disruption.