Research Note

Possible discovery of the r-process characteristics in the abundances of metal-rich barium stars

¹ Department of PhysicsHebei Normal University, 20 Nanerhuan East Road, 050024 Shijiazhuang PR China
e-mail: wycui@bao.ac.cn
² School of Space Science and Physics, Shandong University at Weihai, 264209 Weihai, PR China
³ National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, 100012 Beijing, PR China
⁴ Baoding University, Baoding, 071000 Hebei, PR China

Received: 20 December 2013
Accepted: 22 April 2014

Abstract

Aims. We study the abundance distributions of a sample of metal-rich barium stars provided by Pereira et al. (2011, A&A, 533, A51) to investigate the s- and r-process nucleosynthesis in the metal-rich environment.

Methods. We compared the theoretical results predicted by a parametric model with the observed abundances of the metal-rich barium stars.

Results. We found that six barium stars have a significant r-process characteristic, and we divided the barium stars into two groups: r-rich barium stars (C_r > 5.0, [La/Nd] < 0) and normal barium stars. The behavior of the r-rich barium stars seems more like that of the metal-poor r-rich and CEMP-r/s stars. We suggest that the most possible formation mechanism for these stars is the s-process pollution, although their abundance patterns can be fitted very well when the pre-enrichment hypothesis is included. That we cannot explain them well using the s-process nucleosynthesis alone may be due to our incomplete knowledge on the production of Nd, Eu, and other relevant elements by the s-process in metal-rich and super metal-rich environments (see details in Pereira et al. 2011).