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arXiv · 1606.09318

The odd-isotope fractions of Barium in CEMP-r/s star HE 0338-3945 and r-II star CS 31082-001

Xiaoying Meng·Wenyuan Cui·Jianrong Shi·Xiaohua Jiang·Gang Zhao·Bo Zhang·Ji Li
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Abstract

We report the first measurement of the odd-isotope fractions for barium, \fodd\, in two extremely metal-poor stars: a CEMP-r/s star \he\ (\feh\,$=-2.42\pm0.11$) and an r-II star \cs\ (\feh\,$=-2.90\pm0.13$). The measured \fodd\ values are $0.23\pm0.12$ corresponding to $34.3\pm34.3$\% of the r-process contributions for \he\ and $0.43\pm0.09$ corresponding to $91.4\pm25.7$\% of the r-process contribution to Ba production for \cs. The high r-process signature of barium in \cs\ ($91.4\pm25.7\%$) suggests that the majority of the heavy elements in this star were synthesised via an r-process path, while the lower r-process value ($34.3\pm34.3\%$) found in \he\ indicates that the heavy elements in this star formed through a mix of s-process and r-process synthesis. These conclusions are consistent with studies based on AGB model calculations to fit their abundance distributions.

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Xiaoying Meng, Wenyuan Cui, Jianrong Shi, Xiaohua Jiang, Gang Zhao, Bo Zhang, Ji Li. 2016-06-30. The odd-isotope fractions of Barium in CEMP-r/s star HE 0338-3945 and r-II star CS 31082-001. https://doi.org/10.1051/0004-6361%2F201527318

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