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The study of s-process nucleosynthesis based on barium stars, CEMP-s and CEMP-r/s stars |
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| Authors: | Wenyuan Cui Jianrong Shi Yuanyuan Geng Caixia Zhang Xiaoying Meng Lang Shao Bo Zhang |
| Institution: | 1. Department of Physics, Hebei Normal University, 20 Nanerhuan Dong Road, Yuhua District, Shijiazhuang, 050024, P.R. China 2. National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, 100012, P.R. China 3. Department of Physics, Shandong University, Jinan, Shandong, 250100, P.R. China |
| Abstract: | In order to get a broader view of the s-process nucleosynthesis we study the abundance distribution of heavy elements of 35 barium stars and 24 CEMP-stars, including nine CEMP-s stars and 15 CEMP-r/s stars. The similar distribution of Pb/hs] between CEMP-s and CEMP-r/s stars indicate that the s-process material of both CEMP-s and CEMP-r/s stars should have a uniform origin, i.e. mass transfer from their predominant AGB companions. For the CEMP-r/s stars, we found that the r-process should provide similar proportional contributes to the second s-peak and the third s-peak elements, and also be responsible for the higher overabundance of heavy elements than those in CEMP-s stars. Which hints that the r-process origin of CEMP-r/s stars should be closely linked to the main r-process. The fact that some small r values exist for both barium and CEMP-s stars, implies that the single exposure event of the s-process nucleosynthesis should be general in a wide metallicity range of our Galaxy. Based on the relation between C r and C s, we suggest that the origin of r-elements for CEMP-r/s stars have more sources. A common scenario is that the formation of the binary system was triggered by only one or a few supernova. In addition, accretion-induced collapse(AIC) or SN 1.5 should be the supplementary scenario, especially for these whose pre-AGB companion with higher mass and smaller orbit radius, which support the higher values of both C r and C s. |
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