Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, Hawaii 96720, USA.
Astronomical Institute, Osaka Kyoiku University, Asahigaoka, Kashiwara, Osaka 582-8582, Japan.
Nature. 2015 Feb 19;518(7539):381-4. doi: 10.1038/nature14161.
The origin of lithium (Li) and its production process have long been uncertain. Li could be produced by Big Bang nucleosynthesis, interactions of energetic cosmic rays with interstellar matter, evolved low-mass stars, novae, and supernova explosions. Chemical evolution models and observed stellar Li abundances suggest that at least half the Li may have been produced in red giants, asymptotic giant branch (AGB) stars, and novae. No direct evidence, however, for the supply of Li from evolved stellar objects to the Galactic medium has hitherto been found. Here we report the detection of highly blue-shifted resonance lines of the singly ionized radioactive isotope of beryllium, (7)Be, in the near-ultraviolet spectra of the classical nova V339 Del (Nova Delphini 2013) 38 to 48 days after the explosion. (7)Be decays to form (7)Li within a short time (half-life of 53.22 days). The (7)Be was created during the nova explosion via the alpha-capture reaction (3)He(α,γ)(7)Be (ref. 5). This result supports the theoretical prediction that a significant amount of (7)Li is produced in classical nova explosions.
锂 (Li) 的起源及其生产过程长期以来一直不确定。Li 可能是由大爆炸核合成、高能宇宙射线与星际物质的相互作用、演化的低质量恒星、新星和超新星爆炸产生的。化学演化模型和观测到的恒星 Li 丰度表明，至少有一半的 Li 可能是在红巨星、渐近巨星支 (AGB) 恒星和新星中产生的。然而，到目前为止，还没有发现从演化恒星体向银河介质供应 Li 的直接证据。在这里，我们报告了在经典新星 V339 Del（新星 Delphini 2013）爆炸后 38 至 48 天的近紫外光谱中探测到铍的放射性同位素单离子化 (7)Be 的高度蓝移共振线。(7)Be 在短时间内（半衰期为 53.22 天）衰变为 (7)Li。(7)Be 是在新星爆炸过程中通过 α 捕获反应 (3)He(α,γ)(7)Be（参考文献 5）产生的。这一结果支持了理论预测，即在经典新星爆炸中会产生大量的 (7)Li。
