THE MASS OF THE FIRST STARS

We perform a three-dimensional radiation hydrodynamics simulation to investigate the formation of the first stars from the initial collapse of a primordial gas cloud to the formation and growth of protostars. The simulation is integrated until similar to 0.1 Myr after the formation of the primary protostar, by which time the protostars have already settled onto the main sequence. This work represents the first attempt at simulating the first episodes of star formation, taking into account the ultraviolet radiative feedback effect from multiple protostars as well as the three-dimensional effects of the fragmentation of the accretion disk. We find that the mass accretion onto Population III protostars is significantly suppressed by their radiative feedback. As a result, we find five stars formed in this particular simulation. The final masses of the stars are less than or similar to 60 M-circle dot, including a star of 4.4 M-circle dot. Formation of such a star hints at the existence of even lower-mass stars that would live today.