Volume 548, December 2012
|Number of page(s)||9|
|Published online||19 November 2012|
Origin of the heavy elements in HD 140283
IAG, Universidade de São Paulo, Rua do Matão 1226, Cidade
2 GEPI, Observatoire de Paris, CNRS, UMR 8111, 92195 Meudon Cedex, France
Accepted: 4 October 2012
Context. HD 140283 is a nearby (V = 7.7) subgiant metal-poor star, extensively analysed in the literature. Although many spectra have been obtained for this star, none showed a signal-to-noise (S/N) ratio high enough to enable a very accurate derivation of abundances from weak lines.
Aims. The detection of europium proves that the neutron-capture elements in this star originate in the r-process, and not in the s-process, as recently claimed in the literature.
Methods. Based on the OSMARCS 1D LTE atmospheric model and with a consistent approach based on the spectrum synthesis code Turbospectrum, we measured the europium lines at 4129 Å and 4205 Å, taking into account the hyperfine structure of the transitions. The spectrum, obtained with a long exposure time of seven hours at the Canada-France-Hawaii Telescope (CFHT), has a resolving power of 81 000 and a S/N ratio of 800 at 4100 Å.
Results. We were able to determine the abundance A(Eu) = −2.35 ± 0.07 dex, compatible with the value predicted for the europium from the r-process. The abundance ratio [Eu/Ba] = +0.58 ± 0.15 dex agrees with the trend observed in metal-poor stars and is also compatible with a strong r-process contribution to the origin of the neutron-capture elements in HD 140283.
Key words: Galaxy: halo / stars: abundances / stars: individual: HD 140283
Based on observations within Brazilian time at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientique of France, and the University of Hawaii; Progr. ID 11AB01.
Table A.1 is available in electronic form at http://www.aanda.org
FITS files of the average spectrum are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/548/A42
© ESO, 2012
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