Investigation of the single neutron exposure model for the s-process: the primary nature of the neutron source |
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| Authors: | Kun Ma Wenyuan Cui Bo Zhang |
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| Institution: | Department of Physics, Hebei Normal University, 113 Yuhua Dong Road, Shijiazhuang 050016, China;National Astronomical observatories, Chinese Academy of Sciences, Beijing 100012, China |
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| Abstract: | The primary nature of the 13C neutron source is very significant for the studies of the s -process nucleosynthesis. In this paper we present an attempt to fit the element abundances observed in 16 s -rich stars using parametric model of the single neutron exposure. The calculated results indicate that almost all s -elements were made in a single neutron exposure for nine sample stars. Although a large spread of neutron exposure is obtained, the maximum value of the neutron exposure will reach about 7.0 mbarn?1, which is close to the theoretical predictions by the asymptotic giant branch (AGB) model. The calculated result is a significant evidence for the primary nature of the neutron source. Combining the result obtained in this work and the neutron exposure–initial mass relations, a large spread of neutron exposure can be explained by the different initial stellar mass and their time evolution. The possibility that the rotationally induced mixing process can lead to a spread of the neutron exposure in AGB stars is also existent. |
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| Keywords: | nuclear reactions nucleosynthesis abundances stars: AGB and post-AGB |
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