The R-Process Alliance: First Magellan/MIKE Release from the Southern Search for R-process-enhanced Stars

Extensive progress has recently been made in our understanding of heavy-element production via the r -process in the universe, specifically with the first observed neutron star binary merger (NSBM) event associated with the gravitational-wave signal detected by LIGO, GW170817. The chemical abundance...

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Bibliographic Details
Published in:The Astrophysical journal 2020-08, Vol.898 (2), p.150
Main Authors: Ezzeddine, Rana, Rasmussen, Kaitlin, Frebel, Anna, Chiti, Anirudh, Hinojisa, Karina, Placco, Vinicius M., Ji, Alexander P., Beers, Timothy C., Hansen, Terese T., Roederer, Ian U., Sakari, Charli M., Melendez, Jorge
Format: Article
Language:English
Subjects:
Abundance
Astrophysics
Binary stars
Dwarf galaxies
Equilibrium analysis
Gravitational waves
Iron
Metallicity
Metals
Neutron stars
Spectroscopy
Stars
Thermodynamic equilibrium
Universe
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Summary:Extensive progress has recently been made in our understanding of heavy-element production via the r -process in the universe, specifically with the first observed neutron star binary merger (NSBM) event associated with the gravitational-wave signal detected by LIGO, GW170817. The chemical abundance patterns of metal-poor r -process-enhanced stars provide key evidence for the dominant site(s) of the r -process and whether NSBMs are sufficiently frequent or prolific r -process sources to be responsible for the majority of r -process material in the universe. We present atmospheric stellar parameters (using a nonlocal thermodynamic equilibrium analysis) and abundances from a detailed analysis of 141 metal-poor stars carried out as part of the R -Process Alliance (RPA) effort. We obtained high-resolution “snapshot” spectroscopy of the stars using the MIKE spectrograph on the 6.5 m Magellan Clay telescope at Las Campanas Observatory in Chile. We find 10 new highly enhanced r -II (with [Eu/Fe] > +1.0), 62 new moderately enhanced r -I (+0.3 
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab9d1a