We simulate the formation of a low metallicity ( 10 ^ { -2 } Z _ { \odot } ) stellar cluster in a dwarf galaxy at redshift z \sim 14 . Beginning with cosmological initial conditions , the simulation utilizes adaptive mesh refinement and sink particles to follow the collapse and evolution of gas past the opacity limit for fragmentation , thus resolving the formation of individual protostellar cores . A time- and location-dependent protostellar radiation field , which heats the gas by absorption on dust , is computed by integration of protostellar evolutionary tracks with the mesa code . The simulation also includes a robust non-equilibrium chemical network that self-consistently treats gas thermodynamics and dust-gas coupling . The system is evolved for 18 kyr after the first protostellar source has formed . In this time span , 30 sink particles representing protostellar cores form with a total mass of 81 M _ { \odot } . Their masses range from \sim 0.1 M _ { \odot } to 14.4 M _ { \odot } with a median mass \sim 0.5 - 1 M _ { \odot } . Massive protostars grow by competitive accretion while lower-mass protostars are stunted in growth by close encounters and many-body ejections . In the regime explored here , the characteristic mass scale is determined by the temperature floor set by the cosmic microwave background and by the onset of efficient dust-gas coupling . It seems unlikely that host galaxies of the first bursts of metal-enriched star formation will be detectable with the James Webb Space Telescope or other next-generation infrared observatories . Instead , the most promising access route to the dawn of cosmic star formation may lie in the scrutiny of metal-poor , ancient stellar populations in the Galactic neighborhood . The observable targets that correspond to the system simulated here are ultra-faint dwarf satellite galaxies such as Boötes II , Segue I and II , and Willman I .