The p -process in exploding rotating massive stars
The p -process in exploding rotating massive stars
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旋转大质量恒星爆炸的 p 过程
DOI：
10.1051/0004-6361/202243331
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发表时间：
2022
影响因子：
6.5
通讯作者：
Choplin A
中科院分区：
文献类型：
--
作者：
Choplin A
p-过程核合成可以解释在太阳系中观测到的比铁重的富含质子的同位素，但差异仍然存在（例如Mo和rupp同位素），并且关于p-过程的天体物理位置的一些重要问题仍未得到解答。目的：我们研究爆炸过程是如何运作的旋转大质量恒星经历了一个增强过程核合成在他们的生命中通过旋转混合。方法利用Geneva恒星演化代码，我们计算了金属丰度为z = 10−3、具有不同初始旋转速度和速率的25M⊙恒星模型，用于仍然存在很大不确定性的17o (α,γ)21Ne反应。核合成计算与737种同位素的网络相结合，与恒星演化相结合，并在最后演化阶段和不同能量的球形爆炸的后处理中计算了p过程的核合成。这些爆炸是用相对论流体力学代码模拟的。结果在我们的模型中，核素主要是在爆炸阶段合成的，而在极限静压燃烧阶段合成的较少。p-过程的产量主要取决于初始反式铁种子的数量，而反式铁种子的数量又取决于初始旋转速率。我们发现旋转对p-过程的影响与旋转对这些过程的影响相当。从无旋转到快旋转，质量数a < 140的核素的这一过程产率增加了3 - 4个指数，p-过程产率也增加了。快速旋转，较低的17o （α,γ）率显著产生a≥140的-核素和对核素。过程产率对爆炸能量的依赖性很弱。结论sour的研究结果表明，来自大质量恒星的核心坍缩超新星对太阳（和银河系）p核的贡献在过去被低估了，更具体地说，来自亚太阳金属丰度的大质量恒星的贡献甚至可能占主导地位。一项更详细的研究，包括具有广泛质量和金属丰度的恒星模型，以及基于银河系化学演化的定量分析，仍有待进行。
ContextThep-process nucleosynthesis can explain proton-rich isotopes that are heavier than iron, which are observed in the Solar System, but discrepancies still persist (e.g. for the Mo and Rup-isotopes), and some important questions concerning the astrophysical site(s) of thep-process remain unanswered.AimsWe investigate how thep-process operates in exploding rotating massive stars that have experienced an enhanceds-process nucleosynthesis during their life through rotational mixing.MethodsWith the Geneva stellar evolution code, we computed 25M⊙stellar models at a metallicity ofZ= 10−3with different initial rotation velocities and rates for the still largely uncertain17O(α,γ)21Ne reaction. The nucleosynthesis calculation, followed with a network of 737 isotopes, was coupled to stellar evolution, and thep-process nucleosynthesis was calculated in post-processing during both the final evolutionary stages and spherical explosions of various energies. The explosions were modelled with a relativistic hydrodynamical code.ResultsIn our models, thep-nuclides are mainly synthesized during the explosion, but not much during the ultimate hydrostatic burning stages. Thep-process yields mostly depend on the initial number of trans-iron seeds, which in turn depend on the initial rotation rate. We found that the impact of rotation on thep-process is comparable to the impact of rotation on thes-process. From no to fast rotation, thes-process yields of nuclides with mass numberA< 140 increase by 3−4 dex, and so do thep-process yields. Fast rotation with a lower17O(α,γ) rate significantly producess- andp-nuclides withA≥ 140. The dependence of thep-process yields on the explosion energy is very weak.ConclusionsOur results suggest that the contribution of core-collapse supernovae from massive stars to the solar (and Galactic)p-nuclei has been underestimated in the past, and more specifically, that the contribution from massive stars with sub-solar metallicities may even dominate. A more detailed study including stellar models with a wide range of masses and metallicities remains to be performed, together with a quantitative analysis that is based on the chemical evolution of the Galaxy.