Actinide-rich and Actinide-poor r-process-enhanced Metal-poor Stars Do Not Require Separate r-process Progenitors
Name
Holmbeck_2019_ApJ_881_5.pdf
Description
Published version
Size
10.7 MB
Format
Adobe PDF
Checksum (MD5)
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Author(s)
Holmbeck, Erika M.
Frebel, Anna L.
McLaughlin, G. C.
Mumpower, Matthew R.
Sprouse, Trevor M.
Surman, Rebecca
Date Issued
August 2019
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Citation
Holmbeck, Erika M. et al. "Actinide-rich and Actinide-poor r-process-enhanced Metal-poor Stars Do Not Require Separate r-process Progenitors." Astrophysical Journal 881, 1 (August 2019): 5 © 2019 American Astronomical Society
Version
Final published version
Abstract
The astrophysical production site of the heaviest elements in the universe remains a mystery. Incorporating heavy-element signatures of metal-poor, r-process-enhanced stars into theoretical studies of r-process production can offer crucial constraints on the origin of heavy elements. In this study, we introduce and apply the "actinide-dilution with matching" model to a variety of stellar groups, ranging from actinide-deficient to actinide-enhanced, to empirically characterize r-process ejecta mass as a function of electron fraction. We find that actinide-boost stars do not indicate the need for a unique and separate r-process progenitor. Rather, small variations of neutron richness within the same type of r-process event can account for all observed levels of actinide enhancements. The very low-Y[subscript e], fission-cycling ejecta of an r-process event need only constitute 10%-30% of the total ejecta mass to accommodate most actinide abundances of metal-poor stars. We find that our empirical Y e distributions of ejecta are similar to those inferred from studies of GW170817 mass ejecta ratios, which is consistent with neutron-star mergers being a source of the heavy elements in metal-poor, r-process-enhanced stars.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.3847/1538-4357/ab2a01
