High-spin early stars

High-spin early stars. Stellar nucleosynthesis by exothermic fusion ends with iron, the most tightly bound of all nuclei. Stars produce heavier species by two neutron-capture mechanisms—the rapid “r-process” and the slow “s-process”—and expel them in supernovae or stellar winds. The r-process avails itself of the enormous neutron flux during the supernova to convey nuclei up the atomic-number scale by way of short-lived stages faster than those stages can decay back down. The s-process, making do with weaker neutron fluxes inside quiescent stars, requires long-lived intermediate stages. It was long thought that the s-process occurs only in stars of modest mass. But now Cristina Chiappini (Leibniz Institute for Astrophysics, Potsdam, Germany) and coworkers have reported anomalously high abundances of two s-process products—yttrium and strontium—in spectra of a cluster of Milky Way stars so old that their Y and Sr must have been created in an early generation of very massive stars...