$^{29}$ Si的氢燃烧及其对来自经典新星的太阳前星尘颗粒的影响
Hydrogen burning of $^{29}$Si and its impact on presolar stardust grains from classical novae
摘要：
在原始陨石中发现的前太阳星尘颗粒被认为保留了颗粒凝结时恒星流出的同位素组成。因此，实验室测量其同位素比值是研究恒星演化、恒星爆炸、核合成、混合机制、尘埃形成和星系化学演化等相关问题的敏感探针。对于一些选定的前太阳颗粒，经典新星已被讨论作为一个潜在的来源。对于SiC、硅酸盐和石墨的太阳前颗粒，这种关联是基于观测到的小的$N(^{12}$ C）/$N(^{13}$ C）和$N(^{14}$ N）/ $N(^{15}$ N）数量丰度比与太阳值的比较，以及$^{30}$ Si相对于$^{29}$ Si的丰度过剩，正如先前经典新星模型所预测的那样。我们报告的直接测量的$^{29}$ Si（p，$γ$）$^{30}$ P反应，强烈影响模拟$δ^{29}$硅值从经典新星。我们的新实验$^{29}$ Si（p，$γ$）$^{30}$ P热核反应速率与以前的结果在经典新星温度范围内（$T$ $=$ $100$ $-$ $400$ ~MK）的差异高达50%，而速率的不确定性降低了高达$3$的一个因素。使用我们的新的反应速率在Monte Carlo反应网络和流体动力学模拟的经典新星，我们估计$δ^{29}$ Si值大大减少的不确定性。我们的研究结果建立了$δ^{29}$ Si值测量的前太阳粒作为一个敏感的探针，用于评估其经典的新星亲子关系。我们还表明，$δ^{30}$ Si值从新星模拟目前不是一个有用的诊断工具，除非大的不确定性的$^{30}$ P（p，$γ$）$^{31}$ S反应速率可以显着降低。
英文摘要：
Presolar stardust grains found in primitive meteorites are believed to retain the isotopic composition of stellar outflows at the time of grain condensation. Therefore, laboratory measurements of their isotopic ratios represent sensitive probes for investigating open questions related to stellar evolution, stellar explosions, nucleosynthesis, mixing mechanisms, dust formation, and galactic chemical evolution. For a few selected presolar grains, classical novae have been discussed as a potential source. For SiC, silicate, and graphite presolar grains, the association is based on the observation of small $N(^{12}$C)/$N(^{13}$C) and $N(^{14}$N)/$N(^{15}$N) number abundance ratios compared to solar values, and abundance excesses in $^{30}$Si relative to $^{29}$Si, as previously predicted by models of classical novae. We report on a direct measurement of the $^{29}$Si(p,$γ$)$^{30}$P reaction, which strongly impacts simulated $δ^{29}$Si values from classical novae. Our new experimental $^{29}$Si(p,$γ$)$^{30}$P thermonuclear reaction rate differs from previous results by up to 50\% in the classical nova temperature range ($T$ $=$ $100$ $-$ $400$~MK), while the rate uncertainty is reduced by up to a factor of $3$. Using our new reaction rate in Monte Carlo reaction network and hydrodynamic simulations of classical novae, we estimate $δ^{29}$Si values with much reduced uncertainties. Our results establish $δ^{29}$Si values measured in presolar grains as a sensitive probe for assessing their classical nova paternity. We also demonstrate that $δ^{30}$Si values from nova simulations are presently not a useful diagnostic tool unless the large uncertainty of the $^{30}$P(p,$γ$)$^{31}$S reaction rate can be significantly reduced.
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