We present new SDSS and Washington photometry of the young , outer-halo stellar system , Segue 3 .
Combined with archival VI-observations , our most consistent results yield : Z = 0.006 \pm 0.001 , \log ( Age ) = 9.42 \pm 0.08 , ( m - M ) _ { 0 } = 17.35 \pm 0.08 , E ( B - V ) = 0.09 \pm 0.01 , with a high binary fraction of 0.39 \pm 0.05 , using the Padova models .
We confirm that mass-segregation has occurred , supporting the hypothesis that this cluster is being tidally disrupted .
A 3-parameter King model yields a cluster radius of r _ { cl } = 0. \degr 017 \pm 0. \degr 007 , a core radius of r _ { c } = 0. \degr 003 \pm 0. \degr 001 , and a tidal radius of r _ { t } = 0. \degr 04 \pm 0. \degr 02 .
A comparison of Padova and Dartmouth model-grids indicates that the cluster is not significantly \alpha -enhanced , with a mean \mathrm { [ Fe / H ] } = -0.55 ^ { +0.15 } _ { -0.12 } dex , and a population age of only 2.6 \pm 0.4 Gyr .
We rule out a statistically-significant age-spread at the main-sequence turn-off because of a narrow sub-giant branch , and discuss the role of stellar rotation and cluster age , using Dartmouth and Geneva models : approximately 70 \% of the Seg 3 stars at or below the main-sequence turn-off have enhanced rotation .
Our results for Segue 3 indicate that it is younger and more metal-rich than all previous studies have reported to-date .
From colors involving Washington-C and SDSS-u filters , we identify several giants and a possible blue-straggler for future follow-up spectroscopic studies , and we produce spectral energy distributions of previously known members and potential Segue 3 sources with Washington ( CT _ { 1 } ) , Sloan ( ugri ) , and VI -filters .
Segue 3 shares the characteristics of unusual stellar systems which have likely been stripped from external dwarf galaxies as they are being accreted by the Milky Way , or that have been formed during such an event .
Its youth , metallicity and location are all inconsistent with Segue 3 being a cluster native to the Milky Way .