* Astronomy

Title: Kim 3: an Ultra-faint Star Cluster in the Constellation of Centaurus
Author: Dongwon Kim, Helmut Jerjen, Dougal Mackey, Gary S Da Costa, Antonino P Milone

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±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.

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