J/ApJ/681/1524 Detailed abundances for 28 metal-poor stars (Lai+, 2008)
Detailed abundances for 28 metal-poor stars: stellar relics in the Milky Way. Lai D.K., Bolte M., Johnson J.A., Lucatello S., Heger A., Woosley S.E. <Astrophys. J., 681, 1524-1556 (2008)> =2008ApJ...681.1524L
ADC_Keywords: Equivalent widths ; Abundances, [Fe/H] ; Effective temperatures ; Stars, metal-deficient Keywords: nuclear reactions, nucleosynthesis, abundances - stars: abundances - stars: Population II - supernovae: general Abstract: We present the results of an abundance analysis for a sample of stars with -4<[Fe/H]←2. The data were obtained with the HIRES spectrograph at Keck Observatory. The set includes 28 stars, with effective temperature ranging from 4800 to 6600K. For 13 stars with [Fe/H]←2.6, including nine with [Fe/H]←3.0 and one with [Fe/H]=-4.0, these are the first reported detailed abundances. For the most metal-poor star in our sample, CS 30336-049, we measure an abundance pattern that is very similar to stars in the range [Fe/H]~-3.5, including a normal C+N, abundance. We also find that it has very low but measurable Sr and Ba, indicating some neutron-capture activity even at this low of a metallicity. We explore this issue further by examining other very neutron capture-deficient stars and find that, at the lowest levels, [Ba/Sr] exhibits the ratio of the main r-process. We also report on a new r-process-enhanced star, CS 31078-018. This star has [Fe/H]=-2.85, [Eu/Fe]=1.23, and [Ba/Eu]=-0.51. CS 31078-018 exhibits an "actinide boost," i.e., much higher [Th/Eu] than expected and at a similar level to CS 31082-001. Our spectra allow us to further constrain the abundance scatter at low metallicities, which we then use to fit to the zero-metallicity Type II supernova yields of Heger & Woosley (2008arXiv0803.3161H). We find that supernovae with progenitor masses between 10 and 20M☉ provide the best matches to our abundances. Description: The data were obtained from multiple runs at the HIRES spectrograph at Keck Observatory between 2001 and 2006. We chose our sample from Lai et al. (2004, Cat. J/AJ/128/2402) and metal-poor candidates identified in the photometric sample of Schuster et al. (2004, Cat. J/A+A/422/527). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 79 28 Stellar parameters width.dat 44 12659 Equivalent widths and atomic parameters for the 28 stars (tables 2, 3 and 4 of the paper)
See also: III/211 : Keck/HIRES Sky Line Atlas (Osterbrock+ 1997) J/A+A/305/245 : Fe I in metal-poor stars (Magain+, 1996) J/A+A/356/238 : Atmospheric parameters in metal-poor stars. III. (Carretta+, 2000) J/A+A/404/187 : Equivalent widths for metal-poor stars (Gratton+, 2003) J/AJ/128/2402 : Extremely metal-poor star candidates abundances (Lai+, 2004) J/A+A/422/527 : Metal-poor star uvby-beta photometry. X. (Schuster+, 2004) J/A+A/440/321 : Chemical abundances in 43 metal-poor stars (Jonsell+, 2005) J/A+A/522/A26 : Fe Abundances in metal-poor stars (Sbordone+ 2010) Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Name Star identification 13- 17 F5.2 [Sun] [Fe/H] Metallicity 19- 22 I4 K Teff Effective temperature (1) 24- 27 F4.2 [cm/s2] logg Surface gravity 29- 31 F3.1 km/s vt Microturbulence velocity 33- 37 F5.2 [eV] Chi Slope of the trend for all lines (2) 39- 43 F5.2 --- r Corresponding correlation coefficient for all lines 45- 47 I3 --- N Number of FeI lines used for all lines 49- 53 F5.2 [eV] Chi02 Slope of the trend for χ>0.2eV 55- 59 F5.2 --- r02 Corresponding correlation coefficient for χ>0.2eV 61- 63 I3 --- N02 Number of FeI lines used for χ>0.2eV 65- 69 F5.2 [eV] Chi12 Slope of the trend for χ>1.2eV 71- 75 F5.2 --- r12 Corresponding correlation coefficient for χ>1.2eV 77- 79 I3 --- N12 Number of FeI lines used for χ>1.2eV
Note (1): Effective temperatures are obtained using the V-K color of each star. Note (2): Slope per dex(eV); see section 3.3.1 for more details.
Byte-by-byte Description of file: width.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Name Star designation 13- 19 F7.2 0.1nm Wave Wavelength in Angstroms 21 A1 --- f_Wave [*] Flag on Wave (1) 23- 26 F4.1 --- Element Element identification 28- 32 F5.2 [-] log(gf) Log of the oscillator strength 34- 37 F4.2 eV ExPot Excitation potential 39- 44 F6.2 10-13m EW ? Equivalent width (mÅ)
Note (1): * = abundance was derived through spectral synthesis. Except for the Al lines, all of these lines take into account hyperfine splitting (HFS).
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 03-Nov-2010
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