arXiv 1408.29862014-08-13astro-ph.SR

低金属丰度下核截面对$^{19}$ F核合成的影响

Effects of nuclear cross sections on $^{19}$F nucleosynthesis at low metallicities

S. Cristallo, A. Di Leva, G. Imbriani, L. Piersanti, C. Abia, L. Gialanella, O. Straniero

备注：: 9 pages, 1 figure Accepted for publication on Astronomy & Astrophysics
发表信息：: A&A 570, A46 (2014)
DOI：: 10.1051/0004-6361/201424370

摘要：

氟的起源是核天体物理学中一个长期存在的问题。渐近巨星分支（AGB）星是银河系氟产生的重要贡献者之一。在一般情况下，现存的核合成模型高估了氟生产的AGB恒星的意见。在本文中，我们回顾了有关的核反应速率参与氟的生产/销毁。我们在初始质量M=2 M $_\odot$和Z=0.001的模型上进行这种分析。我们发现主要的不确定性是由于$^{13}$ C（$α$，n）$^{16}$ O，$^{19}$ F（$α$，p）$^{22}$ Ne和$^{14}$ N（p，$γ$）$^{15}$ O反应。在目前实验不确定度范围内的相应反应速率的变化意味着AGB尖端的表面$^{19}$ F变化低于10%。然而，对于某些$α$捕获反应，不能排除这些过程速率的较大变化。因此，我们探讨的影响，一些$α$捕获率的变化远远超出了目前公布的不确定性。通过改变$^{15}$ N（$α$，$γ$）$^{19}$ F和$^{19}$ F（$α$，p）$^{22}$ Ne反应获得最大的$^{19}$ F变化。一些$α$捕获过程的分析，假设一个更广泛的不确定性范围确定$^{19}$ F丰度与最近的光谱氟测量在低金属丰度更好地协议。在后一种情况下，$^{15}$ N（$α$，$γ$）$^{19}$ F和$^{19}$ F（$α$，p）$^{22}$ Ne反应对氟核合成的影响最大。已知的低能量共振的存在使得这种情况即使不太可能，也是可能的。我们计划直接测量这些共振。

英文摘要：

The origin of fluorine is a longstanding problem in nuclear astrophysics. It is widely recognized that Asymptotic Giant Branch (AGB) stars are among the most important contributors to the Galactic fluorine production. In general, extant nucleosynthesis models overestimate the fluorine production by AGB stars with respect to observations. In this paper we review the relevant nuclear reaction rates involved in the fluorine production/destruction. We perform this analysis on a model with initial mass M=2 M$_\odot$ and Z=0.001. We found that the major uncertainties are due to the $^{13}$C($α$,n)$^{16}$O, the $^{19}$F($α$,p)$^{22}$Ne and the $^{14}$N(p,$γ$)$^{15}$O reactions. A change of the corresponding reaction rates within the present experimental uncertainties implies surface $^{19}$F variations at the AGB tip lower than 10\%. For some $α$ capture reactions, however, larger variations in the rates of those processes cannot be excluded. Thus, we explore the effects of the variation of some $α$ capture rates well beyond the current published uncertainties. The largest $^{19}$F variations are obtained by varying the $^{15}$N($α$,$γ$)$^{19}$F and the $^{19}$F($α$,p)$^{22}$Ne reactions. The analysis of some $α$ capture processes assuming a wider uncertainty range determines $^{19}$F abundances in better agreement with recent spectroscopic fluorine measurements at low metallicity. In the framework of the latter scenario the $^{15}$N($α$,$γ$)$^{19}$F and the $^{19}$F($α$,p)$^{22}$Ne reactions show the largest effects on fluorine nucleosynthesis. The presence of poorly known low energy resonances make such a scenario, even if unlikely, possible. We plan to directly measure these resonances.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文