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 ^ { +1.28 } _ { -0.52 } pc and a total luminosity of M _ { V } = +0.7 \pm 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 ^ { +3.0 } _ { -1.7 } Gyr ) and metal-poor ( [ Fe/H ] = -1.6 ^ { +0.45 } _ { -0.30 } ) at a heliocentric distance of 15.14 ^ { +1.00 } _ { -0.28 } 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 .