Discovery of 18 Stars with −3.10 < [Fe/H] < −1.45 in the Sagittarius Dwarf Galaxy
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Chiti_2020_ApJ_901_164.pdf
Description
Published version
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1.02 MB
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Checksum (MD5)
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Author(s)
Chiti, Anirudh
Hansen, Kylie Y.
Frebel, Anna
Date Issued
October 2020
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Citation
Chiti, Anirudh, Hansen, Kylie Y and Frebel, Anna. 2020. "Discovery of 18 Stars with −3.10." Astrophysical Journal, 901 (2).
Version
Final published version
Abstract
© 2020. The American Astronomical Society. All rights reserved. Studies of the early chemical evolution of some larger dwarf galaxies (>107 Me) are limited by the small number of stars known at low metallicities in these systems. Here we present metallicities and carbon abundances for eighteen stars with metallicities between -3.08 < [Fe/H] < -1.47 in the Sagittarius dwarf spheroidal galaxy, using medium-resolution spectra from the MagE spectrograph on the Magellan–Baade Telescope. This sample more than doubles the number of known very metal-poor stars ([Fe/H] < -2.0) in the Sagittarius dwarf galaxy, and identifies one of the first known extremely metal-poor stars ([Fe/H] < -3.0) in the system. These stars were identified as likely metal-poor members of Sagittarius using public, metallicity-sensitive photometry from SkyMapper DR1.1 and proper motion data from Gaia DR2, demonstrating that this dearth of metal-poor stars in some dwarf galaxies can be addressed with targeted searches using public data. We find that none of the stars in our sample are enhanced in carbon, in contrast to the relative prevalence of such stars in the Milky Way halo. Subsequent high-resolution spectroscopy of these stars would be key in detailing the early chemical evolution of the system.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/1538-4357/abb1ae
