KolloquienURL zum ICS-Kalender dieses Seminars
Kirchhoff-Institut für Physik, Otto-Haxel-Hörsaal
Prof. Dr. Anna Frebel, Department of Physics, MIT
KIP, INF 227, Otto-Haxel-Hörsaal
The heaviest chemical elements in the periodic table are synthesized through the rapid neutron-capture (r-)process but the astrophysical site where r-process nucleosynthesis occurs is still unknown. The best candidate sites are ordinary core-collapse supernovae (deaths of massive stars) and mergers of two orbiting exotic neutron stars.
13 billion year old ultra-faint dwarf galaxies preserve a "fossil" record of early chemical enrichment that provides the means to isolate and study clean signatures of individual nucleosynthesis events. Based on new spectroscopic data from the 6.5m Magellan Telescope, we found seven stars in the recently discovered ultra-faint dwarf Reticulum II that show extreme r-process overabundances.
This enhancement implies that the r-process material in Reticulum II was synthesizedin a single prolific event. Our results are clearly incompatible with r-process yields from an ordinary core-collapse supernova but instead consistent with that of a neutron star merger. This first signature of a neutron star merger in the early universe holds the key to finally, after 60 years, identifying the cosmic r-process production site.