IEEE 2017 NSS/MIC/RTSD ControlCenter

Online Program Overview Session: N-01

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NSS Plenary I

Session chair: Lorenzo Fabris Oak Ridge National Laboratory; Sara Pozzi University of Michigan
Shortcut: N-01
Date: Monday, October 23, 2017, 08:00
Room: Centennial III,Centennial IV
Session type: NSS Session


8:00 am N-01-1

Lorenzo Fabris, Sara Pozzi

Introductory Remarks, Awards

8:42 am N-01-2

Chasing the signature of a single prolific r-process event in an ultra-faint dwarf galaxy (#4359)

A. Frebel1

1 MIT, Cambridge, Massachusetts, United States of America


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 synthesized in 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.

Keywords: Plenary Talk