Determination of the stellar reaction rate for 12C(ɑ, γ)16O: using a new expression with the reaction mechanism

doi:10.1088/1674-1056/18/4/023

中国物理B ›› 2009, Vol. 18 ›› Issue (4): 1421-1427.doi: 10.1088/1674-1056/18/4/023

Determination of the stellar reaction rate for ¹²C(ɑ, γ)¹⁶O: using a new expression with the reaction mechanism

徐望¹, 马余刚¹, 蔡翔舟¹, 陈金根¹, 郭威¹, 潘强岩¹, 沈文庆¹, 徐毅², 范功涛², 樊广伟², 罗文², 杨利峰²

(1)Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; (2)Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China;Graduate School of the Chinese Academy of Sciences, Beijing 100039, China

收稿日期:2008-07-01 修回日期:2008-08-18 出版日期:2009-04-20 发布日期:2009-04-20
基金资助:
Project supported partially by the Innovation Program of Science and Technology of the Chinese Academy of Sciences (Grant Nos KJCX2.SW.N13 and KJCX3.SYW.N2), the National Natural Science Foundation of China (Grant Nos 10775167, 10675156 and 10610285), th

Determination of the stellar reaction rate for ¹²C($\alpha$, $\gamma$)¹⁶O: using a new expression with the reaction mechanism

Xu Yi(徐毅)^a)b), Xu Wang(徐望)^a) Ma Yu-Gang(马余刚)^a), Cai Xiang-Zhou(蔡翔舟)^a), Chen Jin-Gen(陈金根)^a), Fan Gong-Tao(范功涛)^a)b), Fan Guang-Wei(樊广伟)^a)b), Guo Wei(郭威)^a), Luo Wen(罗文)^a)b), Pan Qiang-Yan(潘强岩)^a), Shen Wen-Qing(沈文庆)^a), and Yang Li-Feng(杨利峰)^a)b)

^a Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; ^b Graduate School of the Chinese Academy of Sciences, Beijing 100039, China

Received:2008-07-01 Revised:2008-08-18 Online:2009-04-20 Published:2009-04-20
Supported by:
Project supported partially by the Innovation Program of Science and Technology of the Chinese Academy of Sciences (Grant Nos KJCX2.SW.N13 and KJCX3.SYW.N2), the National Natural Science Foundation of China (Grant Nos 10775167, 10675156 and 10610285), th

摘要/Abstract

摘要： The astrophysical reaction rate of ¹²C(α, γ)¹⁶O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T₉=0.2. The existing results even disagree with each other to a certain extent. In this paper, the E1, E2 and total (E1+E2) ¹²C(α,γ)¹⁶O reaction rates are calculated in the temperature range from T₉=0.3 to 2 according to all the available cross section data. A new analytic expression of the ¹²C(α,γ)¹⁶O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3∑gma fit errors, are obtained from fit to our calculated reaction rate from T₉=0.3 to 2. Using the fit results, the analytic expression of ¹²C(α,γ)¹⁶O reaction rate is extrapolated down to T₉=0.05 based on the underlying physics. The ¹²C(α,γ)¹⁶O reaction rate at T₉=0.2 is (8.78\pm1.52)×10¹⁵ cm³s^-1mol^-1. Some comparisons and discussions about our new ¹²C(α, γ)¹⁶O reaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below T₉=2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the ¹²C(α,γ)¹⁶O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our ¹²C(α,γ)¹⁶O reaction rates.

关键词: nucleosynthesis, thermonuclear reaction rate, stellar evolution, supernovae

Abstract: The astrophysical reaction rate of $^{12}$C($\alpha$, $\gamma$)$^{16}$O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at $T_{9}$=0.2. The existing results even disagree with each other to a certain extent. In this paper, the E1, E2 and total (E1+E2) $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rates are calculated in the temperature range from $T_{9}$=0.3 to 2 according to all the available cross section data. A new analytic expression of the $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3$\sigma$ fit errors, are obtained from fit to our calculated reaction rate from $T_{9}$=0.3 to 2. Using the fit results, the analytic expression of $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rate is extrapolated down to $T_{9}$=0.05 based on the underlying physics. The $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rate at $T_{9}$=0.2 is $(8.78\pm1.52)\times10^{15}$\,cm$^{3}$s$^{-1}$mol$^{-1}$. Some comparisons and discussions about our new $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below $T_{9}$=2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rates.

Key words: nucleosynthesis, thermonuclear reaction rate, stellar evolution, supernovae

中图分类号: (3H-, 3He-, and 4He-induced reactions)

25.55.-e

95.30.Cq (Elementary particle processes) 27.20.+n (6 ≤ A ≤ 19) 97.10.Cv (Stellar structure, interiors, evolution, nucleosynthesis, ages)

徐毅, 徐望, 马余刚, 蔡翔舟, 陈金根, 范功涛, 樊广伟, 郭威, 罗文, 潘强岩, 沈文庆, 杨利峰. Determination of the stellar reaction rate for ¹²C(ɑ, γ)¹⁶O: using a new expression with the reaction mechanism[J]. 中国物理B, 2009, 18(4): 1421-1427.

Xu Yi(徐毅), Xu Wang(徐望) Ma Yu-Gang(马余刚), Cai Xiang-Zhou(蔡翔舟), Chen Jin-Gen(陈金根), Fan Gong-Tao(范功涛), Fan Guang-Wei(樊广伟), Guo Wei(郭威), Luo Wen(罗文), Pan Qiang-Yan(潘强岩), Shen Wen-Qing(沈文庆), and Yang Li-Feng(杨利峰). Determination of the stellar reaction rate for ¹²C($\alpha$, $\gamma$)¹⁶O: using a new expression with the reaction mechanism[J]. Chin. Phys. B, 2009, 18(4): 1421-1427.

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Determination of the stellar reaction rate for ¹²C(ɑ, γ)¹⁶O: using a new expression with the reaction mechanism

Determination of the stellar reaction rate for ¹²C($\alpha$, $\gamma$)¹⁶O: using a new expression with the reaction mechanism

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