《自然》20250821出版一周论文导读

 

编译|未玖

Nature,  21 August 2025, Volume 644 Issue 8077

《自然》，2025年8月21日，第644卷，8077期

天文学Astronomy

Extremely stripped supernova reveals a silicon and sulfur formation site

极度剥离的超新星揭示了硅和硫的形成位置

▲ 作者：Steve Schulze, Avishay Gal-Yam et al.

▲链接：

https://www.nature.com/articles/s41586-025-09375-3

▲摘要：

恒星最初由氢和氦的聚变提供能量。这些灰烬在一系列阶段中充当燃料，将大质量恒星转变成壳层结构。这些壳层结构由外部原生氢和内部连续较重的成分组成，预计主要由He、C/O、O/Ne/Mg和O/Si/S组成。硅和硫融合成铁，导致核心坍塌，要么发生超新星爆炸，要么形成黑洞。

剥离恒星的外层氢层被移除后，内部富氦层甚至其下方的C/O层暴露出来，为这种壳层结构及其所反映的宇宙元素产生机制提供了证据。由剥离恒星嵌入星周物质（CSM）壳中产生的超新星类型证实了这一情况。然而，目前尚无直接证据表明，大多数内壳负责产生比氧重的元素。

研究组报道了超新星（SN 2021yfj的发现，由一颗恒星剥离至其富O/Si/S层而产生。他们直接观察到一层厚厚的富Si/S壳层，在超新星爆炸前不久由前身恒星排出。从理论上讲，揭示这样的恒星内层颇具挑战性，可能需要一种很少观测到的质量损失机制。这一罕见的超新星事件揭示了恒星演化的高级阶段，形成了比任何已知大质量恒星表面检测到的更重的元素，包括硅、硫和氩。

▲ Abstract：

Stars are initially powered by the fusion of hydrogen to helium. These ashes serve as fuel in a series of stages, transforming massive stars into a structure of shells. These are composed of natal hydrogen on the outside and consecutively heavier compositions inside, predicted to be dominated by He, C/O, O/Ne/Mg and O/Si/S. Silicon and sulfur are fused into iron, leading to the collapse of the core and either a supernova explosion or the formation of a black hole. Stripped stars, in which the outer hydrogen layer has been removed and the internal He-rich or even the C/O layer below it is exposed, provide evidence for this shell structure and the cosmic element production mechanism it reflects. The supernova types that arise from stripped stars embedded in shells of circumstellar material (CSM) confirm this scenario. However, direct evidence for the most interior shells, which are responsible for producing elements heavier than oxygen, is lacking. Here we report the discovery of the supernova (SN) 2021yfj resulting from a star stripped to its O/Si/S-rich layer. We directly observe a thick, massive Si/S-rich shell, expelled by the progenitor shortly before the supernova explosion. Exposing such an inner stellar layer is theoretically challenging and probably requires a rarely observed mass-loss mechanism. This rare supernova event reveals advanced stages of stellar evolution, forming heavier elements, including silicon, sulfur and argon, than those detected on the surface of any known class of massive stars.

材料科学Materials Science

Electrochemical loading enhances deuterium fusion rates in a metal target

电化学加载提高了金属靶中的氘聚变速率

▲ 作者：Kuo-Yi Chen, Jannis Maiwald et al.

▲链接：

https://www.nature.com/articles/s41586-025-09042-7

▲摘要：

能源应用的核聚变研究旨在创造条件，释放比触发聚变过程所需的更多能量。为了产生有意义的能量，氘等燃料需要在空间上受到限制，以增加粒子的碰撞概率。因此，研究组着手探讨用氘燃料电化学加载金属晶格是否会增加核聚变事件的概率。

他们报告了一个台式聚变反应堆，实现了用氘离子轰击钯金属靶。这些氘离子在钯金属中发生氘-氘聚变反应。研究组发现，将氘原位电化学加载到钯靶中导致氘-氘聚变速率提高了15（2）%。该实验展示了金属靶在电子伏特能级上的电化学加载如何影响兆电子伏特能级上的核反应。

▲ Abstract：

Nuclear fusion research for energy applications aims to create conditions that release more energy than required to initiate the fusion process. To generate meaningful amounts of energy, fuels such as deuterium need to be spatially confined to increase the collision probability of particles. We therefore set out to investigate whether electrochemically loading a metal lattice with deuterium fuel could increase the probability of nuclear fusion events. Here we report a benchtop fusion reactor that enabled us to bombard a palladium metal target with deuterium ions. These deuterium ions undergo deuterium–deuterium fusion reactions within the palladium metal. We showed that the in situ electrochemical loading of deuterium into the palladium target resulted in a 15(2)% increase in deuterium–deuterium fusion rates. This experiment shows how the electrochemical loading of a metal target at the electronvolt energy scale can affect nuclear reactions at the megaelectronvolt energy scale.

Delocalized electrolyte design enables 600 Wh kg