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First Stars. III. A detailed elemental abundance study of four extremely metal-poor giant stars

François, P.; Depagne, E.; Hill, V.; Spite, M.; Spite, F.; Plez, B.; Beers, T. C.; Barbuy, B.; Cayrel, R. and Andersen, J., et al. (2003) In Astronomy & Astrophysics 403(3). p.1105-1114
Abstract
This paper reports detailed abundance analyses for four extremelymetal-poor (XMP) giant stars with [Fe/H]<-3.8, based onhigh-resolution, high-S/N spectra from the ESO VLT (Kueyen/UVES) and LTEmodel atmosphere calculations. The derived [alpha /Fe] ratios in oursample exhibit a small dispersion, confirming previous findings in theliterature, i.e. a constant overabundance of the alpha -elements with avery small (if any) dependence on [Fe/H]. In particular, the very smallscatter we determine for [Si/Fe] suggests that this element shows aconstant overabundance at very low metallicity, a conclusion which couldnot have been derived from the widely scattered [Si/Fe] values reportedin the literature for less metal-poor stars. For the iron-peak... (More)
This paper reports detailed abundance analyses for four extremelymetal-poor (XMP) giant stars with [Fe/H]<-3.8, based onhigh-resolution, high-S/N spectra from the ESO VLT (Kueyen/UVES) and LTEmodel atmosphere calculations. The derived [alpha /Fe] ratios in oursample exhibit a small dispersion, confirming previous findings in theliterature, i.e. a constant overabundance of the alpha -elements with avery small (if any) dependence on [Fe/H]. In particular, the very smallscatter we determine for [Si/Fe] suggests that this element shows aconstant overabundance at very low metallicity, a conclusion which couldnot have been derived from the widely scattered [Si/Fe] values reportedin the literature for less metal-poor stars. For the iron-peak elements,our precise abundances for the four XMP stars in our sample confirm thedecreasing trend of Cr and Mn with decreasing [Fe/H], as well as theincreasing trend for Co and the absence of any trend for Sc and Ni. Incontrast to the significant spread of the ratios [Sr/Fe] and [Ba/Fe], wefind [Sr/Ba] in our sample to be roughly solar, with a much lowerdispersion than previously found for stars in the range -3.5 < [Fe/H]< -2.5.Based on observations made with the ESO Very Large Telescope at ParanalObservatory, Chile (Large Programme ID 165.N-0276(A)).The complete version of Table 5 is only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp:/ /cdsweb.u-strasbg.fr/cgi-bin/qcat?J /A+A/403/1105 (Less)
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keywords
stars: abundances, stars: Population II, Galaxy: abundances, Galaxy: halo, nuclear reactions, nucleosynthesis, abundances
in
Astronomy & Astrophysics
volume
403
issue
3
pages
1105 - 1114
publisher
EDP Sciences
external identifiers
  • wos:000183080400034
  • scopus:0037732843
ISSN
0004-6361
DOI
10.1051/0004-6361:20030438
language
English
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yes
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ef9985cc-0925-4d2d-bb02-a40f3aa77b23 (old id 130528)
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2007-07-13 10:03:30
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@article{ef9985cc-0925-4d2d-bb02-a40f3aa77b23,
  abstract     = {This paper reports detailed abundance analyses for four extremelymetal-poor (XMP) giant stars with [Fe/H]&lt;-3.8, based onhigh-resolution, high-S/N spectra from the ESO VLT (Kueyen/UVES) and LTEmodel atmosphere calculations. The derived [alpha /Fe] ratios in oursample exhibit a small dispersion, confirming previous findings in theliterature, i.e. a constant overabundance of the alpha -elements with avery small (if any) dependence on [Fe/H]. In particular, the very smallscatter we determine for [Si/Fe] suggests that this element shows aconstant overabundance at very low metallicity, a conclusion which couldnot have been derived from the widely scattered [Si/Fe] values reportedin the literature for less metal-poor stars. For the iron-peak elements,our precise abundances for the four XMP stars in our sample confirm thedecreasing trend of Cr and Mn with decreasing [Fe/H], as well as theincreasing trend for Co and the absence of any trend for Sc and Ni. Incontrast to the significant spread of the ratios [Sr/Fe] and [Ba/Fe], wefind [Sr/Ba] in our sample to be roughly solar, with a much lowerdispersion than previously found for stars in the range -3.5 &lt; [Fe/H]&lt; -2.5.Based on observations made with the ESO Very Large Telescope at ParanalObservatory, Chile (Large Programme ID 165.N-0276(A)).The complete version of Table 5 is only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp:/ /cdsweb.u-strasbg.fr/cgi-bin/qcat?J /A+A/403/1105},
  author       = {François, P. and Depagne, E. and Hill, V. and Spite, M. and Spite, F. and Plez, B. and Beers, T. C. and Barbuy, B. and Cayrel, R. and Andersen, J. and Bonifacio, P. and Molaro, P. and Nordström, Birgitta and Primas, F.},
  issn         = {0004-6361},
  keyword      = {stars: abundances,stars: Population II,Galaxy: abundances,Galaxy: halo,nuclear reactions,nucleosynthesis,abundances},
  language     = {eng},
  number       = {3},
  pages        = {1105--1114},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {First Stars. III. A detailed elemental abundance study of four extremely metal-poor giant stars},
  url          = {http://dx.doi.org/10.1051/0004-6361:20030438},
  volume       = {403},
  year         = {2003},
}