We present results of near-IR spectroscopic measurements of 7 star-forming galaxies at 2.1 < z < 2.5 .
Drawn from a large spectroscopic survey of galaxies photometrically pre-selected by their U _ { n } G { \cal R } colors to lie at z \sim 2 , these galaxies were chosen for their bright rest-frame optical luminosities ( K _ { s } \leq 20.0 ) .
Most strikingly , the majority of the sample of 7 galaxies exhibit [ NII ] / { H \alpha } nebular emission line ratios indicative of at least solar H II region metallicities , at a lookback time of 10.5 Gyr .
The broadband colors of the K _ { s } -bright sample indicate that most have been forming stars for more than a Gyr at z \sim 2 , and have already formed stellar masses in excess of 10 ^ { 11 } M _ { \odot } .
The descendants of these galaxies in the local universe are most likely metal-rich and massive spiral and elliptical galaxies , while plausible progenitors for them can be found among the population of z \sim 3 Lyman Break Galaxies .
While the K _ { s } -bright z \sim 2 galaxies appear to be highly evolved systems , their large { H \alpha } luminosities and uncorrected { H \alpha } star-formation rates of 24 - 60 M _ { \odot } \mbox { yr } ^ { -1 } 
indicate that active star formation is still ongoing .
The luminous UV-selected objects presented here comprise more than half of the high-redshift ( z > 1.5 ) tails of current K -band-selected samples such as the K20 and Gemini Deep Deep surveys .