Forming a Primordial Star in a Relic H ii Region

There has been considerable theoretical debate over whether photoionizationand supernova feedback from the first Population III stars facilitate orsuppress the formation of the next generation of stars. We present results froman Eulerian adaptive mesh refinement simulation demonstrating the formation ofa primordial star within a region ionized by an earlier nearby star. Despitethe higher temperatures of the ionized gas and its flow out of the dark matterpotential wells, this second star formed within 23 million years of itsneighbor's death. The enhanced electron fraction within the HII regioncatalyzes rapid molecular hydrogen formation that leads to faster cooling inthe subsequent star forming halos than in the first halos. This "secondgeneration" primordial protostar has a much lower accretion rate because,unlike the first protostar, it forms in a rotationally supported disk ofapprox. 10-100 solar masses. This is primarily due to the much higher angularmomentum of the halo in which the second star forms. In contrast to previouslypublished scenarios, such configurations may allow binaries or multiple systemsof lower mass stars to form. These first high resolution calculations offerinsight into the impact of feedback upon subsequent populations of stars andclearly demonstrate how primordial chemistry promotes the formation ofsubsequent generations of stars even in the presence of the entropy injected bythe first stars into the IGM.Comment: 4 pages, 2 figures. Some revisions, including enhanced discussion of angular momentum issues. Asrophysical Journal, accepte