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

Journal Article · Sat Aug 10 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/773/1/33· OSTI ID:22140288

Ito, Hiroko; Aoki, Wako ^[1]; Beers, Timothy C. ^[2]; Tominaga, Nozomu ^[3]; Honda, Satoshi ^[4]; Carollo, Daniela ^[5]

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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)

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, 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.

• OSTI ID: 22140288
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 773; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ASYMPTOTIC SOLUTIONS
BERYLLIUM
CAPTURE
CARBON
CHEMICAL ANALYSIS
GALAXIES
LITHIUM
METALS
MIXING
NEUTRON REACTIONS
NITROGEN
OXYGEN
RADIAL VELOCITY
STARS