J/ApJ/658/367 Abundances of carbon stars in Galactic halo (Komiya+, 2007)
The origin of carbon enhancement and the initial mass function of extremely
metal-poor stars in the Galactic halo.
Komiya Y., Suda T., Minaguchi H., Shigeyama T., Aoki W., Fujimoto M.Y.
<Astrophys. J., 658, 367-390 (2007)>
=2007ApJ...658..367K 2007ApJ...658..367K
ADC_Keywords: Stars, carbon ; Abundances
Keywords: Galaxy: halo - stars: abundances - stars: carbon - stars: evolution -
stars: luminosity function, mass function
Abstract:
It is known that the carbon-enhanced, extremely metal-poor (CEMP)
stars constitute a substantial proportion of the extremely metal-poor
(EMP) stars of the Galactic halo, and a by far larger proportion than
CH stars among Population II stars. We investigate their origin by
taking into account an additional evolutionary path to the surface
carbon enrichment, triggered by hydrogen engulfment by the helium
flash convection, in EMP stars with [Fe/H]≲-2.5. This process is
distinct from the third dredge-up operating in more metal-rich stars
and in EMP stars. In binary systems of EMP stars, the secondary stars
become CEMP stars through mass transfer from the low- and
intermediate- mass primary stars that have developed the surface
carbon enhancement. Our binary scenario can predict the variations in
the abundances not only for carbon but also for nitrogen and s-process
elements and can reasonably explain the observed properties such as
the stellar distributions of the carbon abundances, the binary
periods, and the evolutionary stages.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 117 34 Observational sample of CEMP star from literature
(Carbon-enhanced, Extremely Metal-Poor stars)
table2.dat 69 87 Observational sample of CH or Ba star from Literature
refs.dat 171 55 References
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See also:
III/227 : General Catalog of galactic Carbon stars, 3d Ed. (Alksnis+ 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 25 A25 --- Des Stellar description (4)
27- 37 A11 --- Name Object name (1)
39 A1 --- n_Name [a] Individual note (2)
41 A1 --- l_Per Limit flag on Per
42- 48 F7.2 d Per ? Orbital Period
49 A1 --- n_Per [?] Uncertainty flag on Per
50 A1 --- f_Per [b] Binarity (3)
52- 55 F4.2 --- e ? Orbital eccentricity
56 A1 --- n_e [?] Uncertainty flag on e
58- 61 F4.2 [cm/s2] logg ? Log of the surface gravity
62 A1 --- n_logg [?] Uncertainty flag on logg
64- 68 F5.2 [Sun] [Fe/H] Log of the Fe/H abundance
70- 73 F4.2 [-] [C/Fe] Log of the C/Fe abundance
75- 78 F4.2 [-] [N/Fe] ? Log of the N/Fe abundance
80 A1 --- l_[O/Fe] Limit flag on [O/Fe]
81- 84 F4.2 [-] [O/Fe] ? Log of the O/Fe abundance
86- 90 F5.2 [-] [Sr/Fe] ? Log of the Sr/Fe abundance
92 A1 --- l_[Ba/Fe] Limit flag on [Ba/Fe]
93- 97 F5.2 [-] [Ba/Fe] Log of the Ba/Fe abundance
99 A1 --- l_[Pb/Fe] Limit flag on [Pb/Fe]
100-103 F4.2 [-] [Pb/Fe] ? Log of the Pb/Fe abundance
105-117 A13 --- Ref Reference(s), in refs.dat file
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Note (1): We select CEMP (Carbon-enhanced, Extremely Metal-Poor) star as
[Fe/H]≲-2.5 and [C/Fe]≥0.5 from literature. Provided that, N rich
star with [Fe/H]≤-2.2 and [C/Fe]≥0.5 also selected.
Note (2): a = CS31062-012 = LP706-7.
Note (3): 'b' indicates a binary: radial velocity variation observed, but
not enough data to estimate period.
Note (4): one of the 3 categories: stars with radial velocity variation,
stars with s-process enhancement, or
stars with no s-process enhancement
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Object name
18- 19 A2 --- Bin [y/n ?] Binarity (1)
21 A1 --- l_Per Limit flag on Per
22- 28 F7.2 d Per ? Orbital period
30- 34 F5.2 [Sun] [Fe/H] ? Log of the Fe/H abundance
36- 40 F5.2 [-] [C/H] ? Log of the C/H abundance
42- 46 F5.2 [-] [C/Fe] ? Log of the C/Fe abundance
48- 52 F5.2 [-] [Ba/Fe] ? Log of the Ba/Fe abundance
54- 57 A4 --- Class Classification (2)
59- 69 A11 --- Ref Reference(s), in refs.dat file
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Note (1): Binarity flag is y=yes, n=no, and y? = a little radial
velocity variation observed, but binarity is not certain
Note (2): Classification as follows:
Ba = barium star
CH = CH star
MDBa = metal deficient barium star
SGCH = sub giant CH star
FBS = field blue straggler
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 43 A20 --- Aut Author's name
45-171 A127 --- Com Comments
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 21-Jan-2009