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Title: CHEMICAL ANALYSIS OF THE NINTH MAGNITUDE CARBON-ENHANCED METAL-POOR STAR BD+44 Degree-Sign 493

We present detailed chemical abundances for the bright carbon-enhanced metal-poor (CEMP) star BD+44 Degree-Sign 493, previously reported on by Ito et al. Our measurements confirm that BD+44 Degree-Sign 493 is an extremely metal-poor ([Fe/H] =-3.8) subgiant star with excesses of carbon and oxygen. No significant excesses are found for nitrogen and neutron-capture elements (the latter of which place it in the CEMP-no class of stars). Other elements that we measure exhibit abundance patterns that are typical for non-CEMP extremely metal-poor stars. No evidence for variations of radial velocity has been found for this star. These results strongly suggest that the carbon enhancement in BD+44 Degree-Sign 493 is unlikely to have been produced by a companion asymptotic giant-branch star and transferred to the presently observed star, nor by pollution of its natal molecular cloud by rapidly-rotating, massive, mega metal-poor ([Fe/H] < - 6.0) stars. A more likely possibility is that this star formed from gas polluted by the elements produced in a ''faint'' supernova, which underwent mixing and fallback, and only ejected small amounts of elements of metals beyond the lighter elements. The Li abundance of BD+44 Degree-Sign 493 (A(Li) = log (Li/H)+12 =1.0) is lower than the Spite plateau value,more » as found in other metal-poor subgiants. The upper limit on Be abundance (A(Be) = log (Be/H)+12 < - 1.8) is as low as those found for stars with similarly extremely-low metallicity, indicating that the progenitors of carbon- (and oxygen-) enhanced stars are not significant sources of Be, or that Be is depleted in metal-poor subgiants with effective temperatures of {approx}5400 K.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Astronomical Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  2. National Optical Astronomy Observatory, Tucson, AZ 85719 (United States)
  3. Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501 (Japan)
  4. Kwasan Observatory, School of Science, Kyoto University, Kyoto 377-0702 (Japan)
  5. Department of Physics and Astronomy, Astronomy, Astrophysics and Astrophotonic Research Center, Macquarie University, North Ryde, NSW 2109 (Australia)
Publication Date:
OSTI Identifier:
22140288
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ASYMPTOTIC SOLUTIONS; BERYLLIUM; CAPTURE; CARBON; CHEMICAL ANALYSIS; GALAXIES; LITHIUM; METALS; MIXING; NEUTRON REACTIONS; NITROGEN; OXYGEN; RADIAL VELOCITY; STARS