The R -Process Alliance: Discovery of a Low- α , r -process-enhanced Metal-poor Star in the Galactic Halo
Name
Sakari_2019_ApJ_874_148.pdf
Description
Published version
Size
2.03 MB
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Adobe PDF
Checksum (MD5)
c5bcf28825e653980b37b0e5ce9126f6
Author(s)
Ezzeddine, Rana
Frebel, Anna L.
Date Issued
April 2019
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Citation
Sakari, Charli M. et al. “The R -Process Alliance: Discovery of a Low- α , r -process-enhanced Metal-poor Star in the Galactic Halo.” Astrophysical Journal, 874, 2 (April 2019): 148 © 2019 The Author(s)
Version
Final published version
Abstract
All rights reserved. A new moderately r-process-enhanced metal-poor star, RAVE J093730.5-062655, has been identified in the Milky Way halo as part of an ongoing survey by the R-Process Alliance. The temperature and surface gravity indicate that J0937-0626 is likely a horizontal branch star. At [Fe/H] = -1.86, J0937-0626 is found to have subsolar [X/Fe] ratios for nearly every light, α, and Fe-peak element. The low [α/Fe] ratios can be explained by an ∼0.6 dex excess of Fe; J0937-0626 is therefore similar to the subclass of "iron-enhanced" metal-poor stars. A comparison with Milky Way field stars at [Fe/H] = -2.5 suggests that J0937-0626 was enriched in material from an event, possibly a Type Ia supernova, that created a significant amount of Cr, Mn, Fe, and Ni and smaller amounts of Ca, Sc, Ti, and Zn. The r-process enhancement of J0937-0626 is likely due to a separate event, which suggests that its birth environment was highly enriched in r-process elements. The kinematics of J0937-0626, based on Gaia DR2 data, indicate a retrograde orbit in the Milky Way halo; J0937-0626 was therefore likely accreted from a dwarf galaxy that had significant r-process enrichment.
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/AB0C02
