Abstract
Historically, the weak s-process contribution to metal-poor stars is thought to be extremely small, due to the effect of the secondary-like nature of the neutron source 22Ne(\(\alpha \), \(n\))25Mg in massive stars, which means that metal-poor “weak s-process stars” could not be found. ET0097 is the first observed carbon-enhanced metal-poor (CEMP) star in the Sculptor dwarf spheroidal galaxy. Because C is enriched and the elements heavier than Ba are not overabundant, ET0097 can be classified as a CEMP-no star. However, this star shows overabundances of lighter n-capture elements (i.e., Sr, Y and Zr). In this work, having adopted the abundance decomposition approach, we investigate the astrophysical origins of the elements in ET0097. We find that the light elements and iron-peak elements (from O to Zn) of the star mainly originate from the primary process of massive stars and the heavier n-capture elements (heavier than Ba) mainly come from the main r-process. However, the lighter n-capture elements such as Sr, Y and Zr should mainly come from the primary weak s-process. The contributed fractions of the primary weak s-process to the Sr, Y and Zr abundances of ET0097 are about 82 %, 84 % and 58 % respectively, suggesting that the CEMP star ET0097 should have the footprints of the weak s-process. The derived result should be a significant evidence that the weak s-process elements can be produced in metal-poor massive stars.
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Acknowledgements
We thank the referee for constructive suggestions which have improved this manuscript significantly. This work has been supported by the National Natural Science Foundation of China under Grants 11673007, 11273011, U1231119, 10973006, 11403007, 11547041 and 11273026, the Natural Science Foundation of Hebei Province under Grant A2011205102, and the Program for Excellent Innovative Talents in University of Hebei Province under Grant CPRC034.
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Yang, G., Li, H., Liu, N. et al. Footprints of the weak s-process in the carbon-enhanced metal-poor star ET0097. Astrophys Space Sci 361, 317 (2016). https://doi.org/10.1007/s10509-016-2906-x
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DOI: https://doi.org/10.1007/s10509-016-2906-x