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J/A+A/501/519 Extremely metal-poor turnoff stars abundances (Bonifacio+, 2009)

First stars. XII. Abundances in extremely metal-poor turnoff stars and comparison with the giants. Bonifacio P., Spite M., Cayrel R., Hill V., Spite F., Francois P., Plez B., Ludwig H.-G., Caffau E., Molaro P., Depagne E., Andersen J., Barbuy B., Beers T.C., Nordstroem B., Primas F. <Astron. Astrophys. 501, 519 (2009)> =2009A&A...501..519B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, halo ; Stars, metal-deficient ; Stars, giant ; Abundances ; Radial velocities ; Equivalent widths ; Stars, population II Keywords: Galaxy: abundances - Galaxy: halo - Galaxy: evolution - stars: abundances - stars: population II - stars: supernovae: general Abstract: The detailed chemical abundances of extremely metal-poor (EMP) stars are key guides to understanding the early chemical evolution of the Galaxy. Most existing data, however, treat giant stars that may have experienced internal mixing later. We aim to compare the results for giants with new, accurate abundances for all observable elements in 18 EMP turnoff stars. VLT/UVES spectra at ∼45000 and S/N ∼130 per pixel (330-1000nm) are analysed with OSMARCS model atmospheres and the TURBOSPECTRUM code to derive abundances for C, Mg, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, and Ba. For Ca, Ni, Sr, and Ba, we find excellent consistency with our earlier sample of EMP giants, at all metallicities. However, our abundances of C, Sc, Ti, Cr, Mn and Co are ∼0.2dex larger than in giants of similar metallicity. Mg and Si abundances are ∼0.2dex lower (the giant [Mg/Fe] values are slightly revised), while Zn is again ∼0.4dex higher than in giants of similar [Fe/H] (6 stars only). For C, the dwarf/giant discrepancy could possibly have an astrophysical cause, but for the other elements it must arise from shortcomings in the analysis. Approximate computations of granulation (3D) effects yield smaller corrections for giants than for dwarfs, but suggest that this is an unlikely explanation, except perhaps for C, Cr, and Mn. NLTE computations for Na and Al provide consistent abundances between dwarfs and giants, unlike the LTE results, and would be highly desirable for the other discrepant elements as well. Meanwhile, we recommend using the giant abundances as reference data for Galactic chemical evolution models. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table7.dat 59 61 Radial velocities of programme giant stars table1.dat 39 19 Adopted model atmosphere parameters for unevolved stars ew.dat 46 1919 Equivalent widths for unevolved stars
See also: J/A+A/403/1105 : Extremely metal-poor giants equivalent widths (Francois+ 2003) J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004) Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Seq [1,35] sequential number of the star 6- 16 A11 --- Name Star name 21- 30 A10 "Y-M-D" Date ? Observation date (1) 36- 48 F13.7 d MJD ? Modified Julian date (JD-2400000.5) of observation (1) 53- 59 F7.2 km/s RV Barycentric radial velocity
Note (1): For star #23 see Depagne et al. (2002A&A...390..187D), for star #35 see Hill et al. (2002A&A...387..560H)
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Seq [1/19] Sequential number of unevolved stars 4- 15 A12 --- Name Star name 17- 20 I4 K Teff Effective temperature 22- 25 F4.2 [cm/s2] logg Surface gravity 27- 29 F3.1 km/s Vt Microturbulent velocity 31- 35 F5.2 [-] [Fe/H] Metallicity 37- 39 A3 --- Rem Remarks
Byte-by-byte Description of file: ew.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Seq [1,19] Sequential number 4- 7 A4 --- Ion Ion identification 10- 17 F8.4 nm lambda Wavelength of the line 19- 23 F5.2 eV chi Excitation potential 26- 31 F6.3 --- loggf Logarithm of the oscillator strength 33- 37 F5.2 pm EW ? Equivalent width 38 A1 --- n_EW [s] abundance from spectrum synthesis (1) 39 A1 --- l_AB Limit flag on AB 40- 45 F6.3 --- AB ? Abundance log(N/H)+12 46 A1 --- n_AB [*] not used for mean (2)
Note (1): 's' (synt) means that the abundance has been obtained by spectrum synthesis and no EW is provided. Note (2): an asterisk (*) means the line has not been used to compute the mean abundance for this star.
Acknowledgements: Piercarlo Bonicacio, Piercarlo.Bonifacio(at) References: Depagne et al., Paper I 2002A&A...390..187D Hill et al., Paper II 2002A&A...387..560H Francois et al., Paper III 2003A&A...403.1105F Cat. J/A+A/403/1105 Sivarani et al., Paper IV 2004A&A...413.1073S Cayrel et al., Paper V 2004A&A...416.1117C Cat. J/A+A/416/1117 Spite et al., Paper VI 2005A&A...430..655S Bonifacio et al., Paper VII 2007A&A...462..851B Francois et al., Paper VIII 2007A&A...476..935F Spite et al., Paper IX 2006A&A...455..291S Sivarani et al., Paper X 2006A&A...459..125S Gonzalez Hernandez et al., Paper XI 2008A&A...480..233G
(End) Patricia Vannier [CDS] 30-Jul-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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