Supernova neutrinos and nucleosynthesis

Observations of metal-poor stars indicate that at least two different nucleosynthesis sites contribute to the production of r-process elements. One site is responsible for the production of light r-process elements Z ? 50, while the other produces the heavy r-process elements. We have analyzed recent observations of metal-poor stars selecting only stars that are enriched in light r-process elements and poor in heavy r-process elements. We find a strong correlation between the observed abundances of the N = 50 elements (Sr, Y and Zr) and Fe. It suggest that neutrino-driven winds from core-collapse supernova are the main site for the production of these elements. We explore this possibility by performing nucleosynthesis calculations based on long-term Boltzmann neutrino transport simulations. We use an equation of state that reproduces recent constrains on the nuclear symmetry energy. We predict that the early ejecta is neutron rich with Ye ? 0.48, it becomes proton rich around 4?s and reaches Ye = 0.586 at 9?s when our simulation stops. The nucleosynthesis in this model produces elements between Zn and Mo, including 92Mo. The elemental abundances are consistent with the observations of the metal-poor star HD 12263. For the elements between Ge and Mo, we produce mainly the neutron-deficient isotopes. This prediction can be confirmed by observations of isotopic abundances in metal-poor stars. No elements heavier than Mo (Z = 42) and no heavy r-process elements are produced in our calculations.

对金属贫困恒星的观测表明，至少两个不同的核合成位点有助于R过程的产生。一个站点负责生产轻型R-Process Elements Z？ 50，而另一个产生重型R-Process元素。我们已经分析了对金属贫困恒星的最新观察结果，这些恒星仅选择富含轻型R-Process元素的恒星，而在重型R过程中较差。我们发现观察到的n = 50个元素（SR，Y和ZR）和Fe的含量之间存在很强的相关性。这表明来自中微子驱动的核心折叠超新星风是产生这些元素的主要位置。我们通过基于长期Boltzmann中微子转运模拟进行核合成计算来探讨这种可能性。我们使用的状态方程将重现对核对称能量的最新约束。我们预测早期的弹射体有富含你们的中子吗？ 0.48，当我们的模拟停止时，它变成了富含4 s的质子，并在9 s时达到ye = 0.586。该模型中的核合成产生Zn和MO之间的元素，包括92MO。元素丰度与金属贫困星HD 12263的观察结果一致。对于GE和MO之间的元素，我们主要产生中子缺陷的同位素。通过观察金属贫困星中同位素丰度的观察，可以证实这一预测。在我们的计算中，没有比MO（Z = 42）重的元素（Z = 42），也没有产生重的R-Process元素。