Spyrou A, Richman D, Couture A, Fields C E, Liddick S N, Childers K, Crider B P, DeYoung P A, Dombos A C, Gastis P, Guttormsen M, Hermansen K, Larsen A C, Lewis R, Lyons S, Midtbø J E, Mosby S, Muecher D, Naqvi F, Palmisano-Kyle A, Perdikakis G, Prokop C, Schatz H, Smith M K, Sumithrarachchi C, Sweet A
Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI, USA.
Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA.
Nat Commun. 2024 Nov 7;15(1):9608. doi: 10.1038/s41467-024-54040-4.
Massive stars are a major source of chemical elements in the cosmos, ejecting freshly produced nuclei through winds and core-collapse supernova explosions into the interstellar medium. Among the material ejected, long-lived radioisotopes, such as Fe (iron) and Al (aluminum), offer unique signs of active nucleosynthesis in our galaxy. There is a long-standing discrepancy between the observed Fe/Al ratio by γ-ray telescopes and predictions from supernova models. This discrepancy has been attributed to uncertainties in the nuclear reaction networks producing Fe, and one reaction in particular, the neutron-capture on Fe. Here we present experimental results that provide a strong constraint on this reaction. We use these results to show that the production of Fe in massive stars is higher than previously thought, further increasing the discrepancy between observed and predicted Fe/Al ratios. The persisting discrepancy can therefore not be attributed to nuclear uncertainties, and points to issues in massive-star models.
大质量恒星是宇宙中化学元素的主要来源，它们通过恒星风以及核心坍缩超新星爆发将新产生的原子核喷射到星际介质中。在喷射出的物质中，诸如铁（Fe）和铝（Al）等长寿命放射性同位素为我们银河系中活跃的核合成提供了独特的标志。伽马射线望远镜观测到的铁/铝比率与超新星模型的预测之间长期存在差异。这种差异被归因于产生铁的核反应网络中的不确定性，特别是铁的中子俘获这一反应。在此，我们展示了对该反应施加有力限制的实验结果。我们利用这些结果表明，大质量恒星中铁的产量比之前认为的更高，这进一步加大了观测到的与预测的铁/铝比率之间的差异。因此，持续存在的差异不能归因于核方面的不确定性，而是指向了大质量恒星模型中存在的问题。
