The First Stars
  Pop III stars are the key to the character of primeval galaxies, the first heavy elements, the onset of cosmological reionization, and the seeds of supermassive black holes. Unfortunately, in spite of their increasing sophistication, numerical models of Pop III star formation cannot yet predict the masses of the first stars. Because they lie at the edge of the observable universe, individual Pop III stars will also remain beyond the reach of telescopes for the foreseeable future, and so their properties remain unknown. However, it will soon be possible to constrain their masses by the direct detection of their supernovae and by reconciling their nucleosynthetic yields to the chemical abundances measured in ancient metal-poor stars in the Galactic halo, some of which may be bear the ashes of the first stars. Here, I review current problems on the simulation frontier in Pop III star formation and discuss the best prospects for constraining their properties observationally in the near term. 
Daniel J. Whalen
astro-ph.CO