Origin of the heavy elements in HD 140283. Measurement of europium abundance

Abstract

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. 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. 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 81000 and a S/N ratio of 800 at 4100 Å. We were able to determine the abundance A(Eu)=-2.35 dex, compatible with the value predicted for the europium from the r-process. The abundance ratio [Eu/Ba]=+0.58 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.

arXiv comment10 pages, 7 figures. To be published in A\&A

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Cited by in corpus (12)

• JINAbase: A database for chemical abundances of metal-poor stars
• High-resolution abundance analysis of very metal-poor r-I stars
• Benchmark stars for Gaia: fundamental properties of the Population II star HD140283 from interferometric, spectroscopic and photometric data
• Abundance patterns of the light neutron-capture elements in very and extremely metal-poor stars
• Heavy elements Ba, La, Ce, Nd, and Eu in 56 Galactic bulge red giants
• High-resolution abundance analysis of HD 140283
• The R-Process Alliance: J1521-3538, a very metal-poor, extremely r-process-enhanced star with [Eu/Fe]=+2.2, and the class of r-III stars
• A three-dimensional hydrodynamical line profile analysis of iron lines and barium isotopes in HD140283
• 12C/13C ratio and CNO abundances in the classical very old metal-poor dwarf HD 140283
• Study of the element abundances in HD 140283: the abundance robustness of the weak r- and main r-process stars
• Neutron-capture elements in a sample of field metal-poor N-rich dwarfs
• A statistical method for the identification of stars enriched in neutron-capture elements from medium-resolution spectra