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- Title
Origin of the heavy elements in HD 140283 Measurement of europium abundance.
- Authors
Siqueira Mello Jr., C.; Barbuy, B.; Spite, M.; Spite, F.
- Abstract
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.
- Subjects
SUBGIANT stars; SPECTRUM analysis; EUROPIUM; NEUTRON capture; ATMOSPHERIC models; LARGE astronomical telescopes
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2012, Vol 548, Issue 1, pA42-1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/201220100