恒星氦燃烧阶段3α反应和^(12)C(α,γ)^(16)O反应相互竞争,两者的反应率共同决定了氦燃烧结束后^(12)C与^(16)O的丰度比,该比值是大质量恒星后继演化以及伴随的元素核合成过程的初始条件。目前,氦燃烧^(12)C(α,γ)^(16)O反应起始T_9=...恒星氦燃烧阶段3α反应和^(12)C(α,γ)^(16)O反应相互竞争,两者的反应率共同决定了氦燃烧结束后^(12)C与^(16)O的丰度比,该比值是大质量恒星后继演化以及伴随的元素核合成过程的初始条件。目前,氦燃烧^(12)C(α,γ)^(16)O反应起始T_9=0.2处,天体物理模型要求的反应率的精确度要低于10%,然而尚未有实验或理论给出满足要求的结果。最为直接和可靠地获取^(12)C(α,γ)^(16)O反应率的方法,就是尽可能往低能区测量其天体物理S因子,然后通过理论外推到感兴趣的能区。为此基于经典的R-矩阵理论,建立了适用于低能核反应的多道、多能级的约化R-矩阵理论来拟合几乎所有可用的^(16)O系统的实验数据。配合使用协方差统计和误差传播理论,拟合外推得到了客观的、内部自恰的和唯一性好的^(12)C(α,γ)^(16)O反应天体物理S因子。总的外推S因子STOT(0.3 Me V)=162.7±7.3 keV·b,理论上首次给出达到恒星演化与元素核合成模型的最低要求的S因子。基于计算给出的全能区的S因子,数值积分给出了温度位于0.04≤T_9≤10的^(12)C(α,γ)^(16)O天体物理反应率。在T_9=0.2处,推荐的反应率为(7.83±0.35)×10^(-15)cm^3mol^(-1)s^(-1)。展开更多
The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analys...The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analyses of the system are made in this paper by using the theory of nonequilibrium dynamics. It is showed that, in the nuclear reaction regions extending from the center to about 0.38 times of the radius of the sun, the gravitational field enables the core 3He nuclear reaction-diffusion system to become unstable and, after the instability, new states to appear in the system have characteristic of time oscillation. This may change the production rates of both 7Be and 8B neutrinos.展开更多
文摘恒星氦燃烧阶段3α反应和^(12)C(α,γ)^(16)O反应相互竞争,两者的反应率共同决定了氦燃烧结束后^(12)C与^(16)O的丰度比,该比值是大质量恒星后继演化以及伴随的元素核合成过程的初始条件。目前,氦燃烧^(12)C(α,γ)^(16)O反应起始T_9=0.2处,天体物理模型要求的反应率的精确度要低于10%,然而尚未有实验或理论给出满足要求的结果。最为直接和可靠地获取^(12)C(α,γ)^(16)O反应率的方法,就是尽可能往低能区测量其天体物理S因子,然后通过理论外推到感兴趣的能区。为此基于经典的R-矩阵理论,建立了适用于低能核反应的多道、多能级的约化R-矩阵理论来拟合几乎所有可用的^(16)O系统的实验数据。配合使用协方差统计和误差传播理论,拟合外推得到了客观的、内部自恰的和唯一性好的^(12)C(α,γ)^(16)O反应天体物理S因子。总的外推S因子STOT(0.3 Me V)=162.7±7.3 keV·b,理论上首次给出达到恒星演化与元素核合成模型的最低要求的S因子。基于计算给出的全能区的S因子,数值积分给出了温度位于0.04≤T_9≤10的^(12)C(α,γ)^(16)O天体物理反应率。在T_9=0.2处,推荐的反应率为(7.83±0.35)×10^(-15)cm^3mol^(-1)s^(-1)。
文摘The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analyses of the system are made in this paper by using the theory of nonequilibrium dynamics. It is showed that, in the nuclear reaction regions extending from the center to about 0.38 times of the radius of the sun, the gravitational field enables the core 3He nuclear reaction-diffusion system to become unstable and, after the instability, new states to appear in the system have characteristic of time oscillation. This may change the production rates of both 7Be and 8B neutrinos.
