J/ApJ/773/33 Chemical analysis of the metal-poor subgiant BD+44 493 (Ito+, 2013)
Chemical analysis of the ninth magnitude carbon-enhanced metal-poor star
BD+44 493.
Ito H., Aoki W., Beers T.C., Tominaga N., Honda S., Carollo D.
<Astrophys. J., 773, 33 (2013)>
=2013ApJ...773...33I 2013ApJ...773...33I
ADC_Keywords: Stars, metal-deficient ; Stars, carbon ; Abundances ;
Equivalent widths
Keywords: Galaxy: abundances; stars: abundances;
stars: individual: BD+44 493; stars: Population II
Abstract:
We present detailed chemical abundances for the bright carbon-enhanced
metal-poor (CEMP) star BD+44°493, previously reported on by
Ito et al. (2009ApJ...698L..37I 2009ApJ...698L..37I). Our measurements confirm that
BD+44°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°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°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 ∼5400K.
Description:
BD+44 493 was observed with the High Dispersion Spectrograph (HDS) at
the Subaru Telescope in 2008 August, October, and November, during an
open-use intensive program (PI: W. Aoki) for high-resolution follow-up
spectroscopy of very and extremely metal-poor stars discovered with
the SDSS/SEGUE survey (Yanny et al. 2009, J/AJ/137/4377).
Objects:
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RA (ICRS) DE Designation(s)
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02 26 49.74 +44 57 46.5 BD+44 493 = TYC 2843-1104-1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 39 409 Line data and equivalent widths
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See also:
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
II/215 : uvby-beta Catalogue (Hauck+ 1997)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013)
J/MNRAS/412/843 : SAGA extremely metal-poor stars (Suda+, 2011)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/A+A/503/541 : Li in late-type stars non-LTE calculations (Lind+, 2009)
J/A+A/501/519 : Extremely metal-poor stars abundances (Bonifacio+, 2009)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/A+A/497/497 : Physical parameters from JHK flux (Gonzalez-Hernandez+, 2009)
J/ApJ/704/750 : Rotational behavior of metal-poor stars (Cortes+, 2009)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
J/ApJ/658/367 : Abundances of carbon stars in Galactic halo (Komiya+, 2007)
J/AJ/132/137 : Abundances of EMP carbon stars (Cohen+, 2006)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/AJ/107/1577 : Halo red giants reddening (Anthony-Twarog+, 1994)
J/AJ/87/1165 : Reddening Maps derived from HI & Galaxy Cts (Burstein+ 1982)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ion Species identifier
7- 14 F8.3 0.1nm lambda [3118/7772] Wavelength
16- 21 F6.3 [-] log(gf) [-9.9/0.6] Log of the oscillator strength
23- 27 F5.3 eV LEP [0/9.2] Lower excitation potential
29 A1 --- l_EW Limit flag on EW (1)
30- 35 F6.2 10-13m EW [0.2/125.3] Equivalent width; milli-Angstroms
37- 39 A3 --- Note Additional remarks (1)
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Note (1):
Syn = Analyzed by the spectrum synthesis to determine the
upper limit of the abundance.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Feb-2015