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. =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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- See also: III/227 : General Catalog of galactic Carbon stars, 3d Ed. (Alksnis+ 2001) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Byte-by-byte Description of file: refs.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 I2 --- Ref Reference number 4- 22 A19 --- BibCode BibCode 24- 43 A20 --- Aut Author's name 45-171 A127 --- Com Comments -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Patricia Vannier [CDS] 21-Jan-2009