The R-process Alliance: first release from the southern search for R-process-enhanced stars in the galactic halo
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Hansen_2018_ApJ_858_92.pdf
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Author(s)
Hansen, Terese T.
Holmbeck, Erika M.
Beers, Timothy C.
Placco, Vinicius M.
Roederer, Ian U.
Frebel, Anna
Sakari, Charli M.
Simon, Joshua D.
Thompson, Ian B.
Date Issued
May 2018
Journal
Astrophysical journal
Publisher
American Astronomical Society
Citation
Hansen, Terese T., et al., "The R-process Alliance: first release from the southern search for R-process-enhanced stars in the galactic halo." Astrophysical journal 858, 2 (May 2018): no. 92 doi 10.3847/1538-4357/AABACC ©2018 Author(s)
Version
Final published version
Abstract
The recent detection of a binary neutron star merger and the clear evidence of the decay of radioactive material observed in this event have, after 60 years of effort, provided an astrophysical site for the rapid neutron-capture (r-) process which is responsible for the production of the heaviest elements in our universe. However, observations of metal-poor stars with highly enhanced r-process elements have revealed abundance patterns suggesting that multiple sites may be involved. To address this issue, and to advance our understanding of the r-process, we have initiated an extensive search for bright (V < 13.5), very metal-poor ([Fe/H] < -2) stars in the Milky Way halo exhibiting strongly enhanced r-process signatures. This paper presents the first sample collected in the southern hemisphere using the echelle spectrograph on du Pont 2.5 m telescope at Las Campanas Observatory. We have observed and analyzed 107 stars with -3.13 < [Fe/H] < -0.79. Of those, 12 stars are strongly enhanced in heavy r-process elements (r-II), 42 stars show moderate enhancements of heavy r-process material (r-I), and 20 stars exhibit low abundances of the heavy r-process elements and higher abundances of the light r-process elements relative to the heavy ones (limited-r). This search is more successful at finding r-process-enhanced stars compared to previous searches, primarily due to a refined target selection procedure that focuses on red giants. ©2018
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.3847/1538-4357/AABACC
