60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae
60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae
复制标题
地球上沉积的 60Fe 和 244Pu 限制了最近附近超新星的 r 过程产量
作者：
Anton Wallner;M. Froehlich;Michael Hotchkis;Norikazu Kinoshita;Michael Paul;M. Martschini;S. Pavetich;S. Tims;N. Kivel;Dorothea Schumann;M. Honda;Hiroyuki Matsuzaki;T. Yamagata
来自超新星的天然钚快速中子俘获过程(r过程)产生许多重化学元素，但其发生的天体物理环境尚不清楚。领先的候选者是中子星合并和某些类型的超新星。Wallner等人。分析了深海地壳样本中的钚含量，确定了在过去数百万年内送到地球的几十个r过程同位素钚-244的原子。同时还有铁-60的信号，这是已知在超新星中产生的。比较这些同位素的比率可以限制超新星和中子星合并对r过程核合成的相对贡献。科学上，这个问题，742页，深海地壳样本中自然产生的钚限制了附近超新星的核合成。一半比铁重的化学元素是由快速中子俘获过程(r过程)产生的。这一过程的地点和产额存在争议，候选对象包括某些类型的超新星(SNE)和中子星的合并。我们在太平洋地壳的样本中寻找两个同位素特征-铁-60(60Fe)(半衰期，260万年)，它主要产生于大质量恒星中，并在超新星爆炸中喷出；钚-244(244Pu)(半衰期，8060万年)，仅在r过程事件中产生。在过去的1000万年里，我们探测到两次不同的60Fe流入地球，伴随而来的是244Pu的较少数量。两个事件的244Pu/60Fe流入率相似。如果SNE主导r-过程核合成，244Pu的流入低于预期，这意味着其他来源的贡献。
Natural plutonium from supernovae The rapid neutron capture process (r-process) produces many of the heavy chemical elements, but the astrophysical settings where it occurs remain unclear. Leading candidates are neutron star mergers and some types of supernovae. Wallner et al. analyzed the plutonium content of a deep-sea crust sample, identifying a few dozen atoms of the r-process isotope plutonium- 244 that were delivered to Earth within the past few million years. There was a simultaneous signal of iron-60, which is known to be produced in supernovae. Comparing the ratios of these isotopes constrains the relative contributions of supernovae and neutron star mergers to r-process nucleosynthesis. Science, this issue p. 742 Naturally occurring plutonium in a deep-sea crust sample constrains nucleosynthesis in nearby supernovae. Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust—iron-60 (60Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and plutonium-244 (244Pu) (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of 60Fe to Earth in the last 10 million years and accompanying lower quantities of 244Pu. The 244Pu/60Fe influx ratios are similar for both events. The 244Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.
影响因子：
64.8
作者：
Kasen, Daniel;Metzger, Brian;Ramirez-Ruiz, Enrico
通讯作者：
Ramirez-Ruiz, Enrico