编译|冯维维

Science, 22 JAN 2026, VOLUME 391, ISSUE 6783

《科学》2026年1月22日，第391卷，6783期

物理学Physics

A second planetesimal collision in the Fomalhaut system

北落师门系统中的第二起星子碰撞

▲ 作者：PAUL KALAS, JASON J. WANG, MAXWELL A. MILLAR-BLANCHAER, BIN B. REN, MARK C. WYATT, GRANT M. KENNEDY, MAXIMILIAN SOMMER, THOMAS M. ESPOSITO, ROBERT J. DE ROSA, AND MICHAEL FITZGERALD

▲链接：

https://www.science.org/doi/10.1126/science.adu6266

▲摘要：

近距恒星北落师门被一个致密源“北落师门b”围绕，先前它曾被解释为一颗尘埃包裹的系外行星，或是由两颗星子碰撞产生的尘埃云。这类碰撞极少被观测到，但其碎片可通过直接成像显现。

研究者报告了哈勃空间望远镜的观测结果，显示在2023年北落师门周围出现了第二个点源，与20年前北落师门b的出现方式相似。他们将这个新增的源解释为两颗星子近期撞击产生的尘埃云。这两个撞击生成的尘埃云在20年间的位置和运动，为研究该碎片带中的碰撞动力学提供了约束条件。

▲ Abstract：

The nearby star Fomalhaut is orbited by a compact source, Fomalhaut b, which has previously been interpreted as either a dust-enshrouded exoplanet or a dust cloud generated by the collision of two planetesimals. Such collisions are rarely observed, but their debris can appear in direct imaging. We report Hubble Space Telescope observations that show the appearance in 2023 of a second point source around Fomalhaut, resembling the appearance of Fomalhaut b 20 years earlier. We interpret this additional source as a dust cloud produced by a recent impact between two planetesimals. The positions and motion of two impact-generated dust clouds over 20 years provide constraints on the collisional dynamics in the debris belt.

Reentry and disintegration dynamics of space debris tracked using seismic data

利用地震数据追踪空间碎片的再入与解体动力学

▲ 作者：BENJAMIN FERNANDO HTTPS://ORCID.ORG/0000-0002-7321-8401 AND CONSTANTINOS CHARALAMBOUS HTTPS://ORCID.ORG/0000-0002-9139-3895Authors Info & Affiliations

▲链接：

https://www.science.org/doi/10.1126/science.adz4676

▲摘要：

随着地球轨道日益拥挤，再入空间碎片带来的风险持续增加。目前，对不受控再入事件的应对受到以下制约：一旦航天器在大气层中开始燃烧，便无法可靠追踪，导致碎片坠落地点预测不准。研究者展示了一种最小梯度拟合地震反演方法，能够较快地辨识出碎片在大气层内的轨迹、速度、高度、下降角度、尺寸以及解体模式。

他们使用2024年神舟十五号再入的开源数据对该方法进行了测试，得出的坠落位置显著偏南于预测轨迹。对级联式、多重解体的观测，为理解碎片解体动力学提供了新的视角，这对空间态势感知和碎片危害减缓具有明确的意义。

▲ Abstract：

The risks posed by reentering space debris continue to grow as Earth’s orbit becomes more crowded. Currently, responses to uncontrolled reentries are hampered by an inability to reliably track spacecraft once they are burning up within the atmosphere, meaning that debris fallout locations are poorly predicted. We have demonstrated a minimum-gradient fit seismic inversion methodology that allows in-atmosphere debris trajectory, speed, altitude, descent angle, size, and fragmentation pattern to be discerned relatively quickly. We tested this methodology on open-source data from the 2024 reentry of Shenzhou-15, deriving a location significantly south of the predicted track. Observations of cascading, multiplicative fragmentation offer insight into debris disintegration dynamics, with clear implications for space situational awareness and debris hazard mitigation.

Observation of one-dimensional, charged domain walls in ferroelectric ZrO₂

氧化锆铁电体中一维带电畴壁的观测

▲ 作者：HAI ZHONG, SHIYU WANG, QINGHUA ZHANG, ZHUOHUI LIU, DONGGANG XIE, JIALI LU, SHIFENG JIN, SHUFANG ZHANG, ER-JIA GUO, AND CHEN GE

▲链接：

https://www.science.org/doi/10.1126/science.aeb7280

▲摘要：

具有纳米级厚度和束缚电荷的铁电带电畴壁通常被视为畴壁纳米电子学中可重构、高导电的超薄二维组件。此类极性拓扑结构的维度限制有望提高器件密度并解锁新功能。研究者报道了具有一维特性的180°头对头与尾对尾带电畴壁。

这些一维带电畴壁被限制在铁电氧化锆的极性层内，其宽度和厚度均具有原子级尺度。定量分析揭示了一种独特的畴壁屏蔽机制：束缚的极化电荷通过氧占位自平衡得以补偿。研究者展示了电场驱动下对这些一维带电畴壁的操控，揭示了极化翻转与氧离子输运之间的微观耦合关系。

▲ Abstract：

Ferroelectric charged domain walls (CDWs) with nanoscale thickness and bound charges are typically viewed as ultrathin, reconfigurable, and highly conductive two-dimensional components for domain wall nanoelectronics. Dimensional confinement of such polar topological structures has the potential to increase device density and unlock novel functionalities. We report 180° head-to-head and tail-to-tail CDWs exhibiting one-dimensional (1D) characteristics. These 1D CDWs are confined within the polar layers of ferroelectric ZrO₂ and have atomic-scale dimensions in both width and thickness. Quantitative analysis unveils a distinct screening mechanism of these walls whereby bound polarization charges are compensated by self-balancing oxygen occupancy. We demonstrate electric field–driven manipulation of these 1D CDWs, revealing the microscopic coupling between polarization switching and oxygen-ion transport.

Observation of the Einstein–de Haas effect in a Bose–Einstein condensate

玻色—爱因斯坦凝聚体中爱因斯坦—德哈斯效应的观测

▲ 作者：HIROKI MATSUI, YUKI MIYAZAWA, RYOTO GOTO, CHIHIRO NAKANO, YUKI KAWAGUCHI, MASAHITO UEDA, AND MIKIO KOZUMA

▲链接：

https://www.science.org/doi/10.1126/science.adx2872

▲摘要：

爱因斯坦—德哈斯效应是一种角动量从微观自旋转移到宏观刚体机械旋转的现象。研究者报告了在自旋—偶极玻色—爱因斯坦凝聚体中观测到爱因斯坦—德哈斯效应，其中固有的磁偶极—偶极相互作用介导了角动量从原子自旋到量子流体集体循环的相干转移。

去极化的自旋组分显示出环状密度分布，通过物质波干涉测量法证实其为量子化涡旋，揭示了自旋角动量与轨道角动量之间的相干转化。这一观测为探索具有手征对称性破缺的基态相、自旋织构、质量循环以及偶极量子气体中的巴尼特效应开辟了新途径。

▲ Abstract：

The Einstein–de Haas effect is a phenomenon in which angular momentum is transferred from microscopic spins to mechanical rotation of a macroscopic rigid body. We report an observation of the Einstein–de Haas effect in a spinor-dipolar Bose–Einstein condensate, in which the intrinsic magnetic dipole-dipole interaction mediates coherent transfer of angular momentum from atomic spins to collective circulation of a quantum fluid. The depolarized spinor components displayed ring-shaped density distributions that were confirmed as quantized vortices through matter-wave interferometry, revealing a coherent conversion between spin and orbital angular momentum. This observation opens a pathway to exploring ground-state phases with broken chiral symmetry, spin textures, and mass circulation, as well as the Barnett effect in dipolar quantum gases.

生命科学Life Science

Endogenous retroviruses synthesize heterologous chimeric RNAs to reinforce human early embryo development

内源性逆转录病毒通过合成异源嵌合RNA增强人类早期胚胎发育

▲ 作者：YANGQUAN XIANG, YULI QIAN, ZHENGYI LI, JIAXU WANG, RUONAN TIAN, WEIKANG MENG, JIABAO BU, FEI HUANG, ZHIPENG AI , AND HONGQING LIANG

▲链接：

https://www.science.org/doi/10.1126/science.adv5257

▲摘要：

合子基因组激活标志着胚胎基因组从休眠状态被唤醒的关键时刻。研究者发现，一种古老病毒残留——内源性逆转录病毒MLT2A1——在人类合子基因组激活过程中发挥着至关重要的作用。MLT2A1在合子基因组激活期间通过与多种下游序列融合，产生嵌合RNA。

这些嵌合RNA与众多合子基因组激活基因相互作用，形成一个自扩增网络，从而在合子基因组激活过程中促进广泛的、全新的基因激活。降低MLT2A1的活性会阻止人类早期胚胎的发育。这表明，古老的病毒序列已被重新利用来调控人类生命的开端，这一发现可能对生殖医学具有重要意义。

▲ Abstract：

Zygotic genome activation (ZGA) marks the critical moment when the embryo’s genome is awakened from dormancy. Xiang et al. now show that an ancient viral remnant, the endogenous retrovirus MLT2A1, plays an essential role in human ZGA. MLT2A1 produces chimeric RNAs during ZGA by fusing with various downstream sequences. These chimeras interact with numerous ZGA genes and form an auto-amplifying network promoting widespread, de novo gene activation during ZGA. Reducing MLT2A1 activity halts early human embryo development. Thus, ancient viral sequences have been repurposed to orchestrate the very beginning of human life, a finding that may have relevance for reproductive medicine.

Myelin is repaired by constitutive differentiation of oligodendrocyte progenitors

髓鞘通过少突胶质祖细胞的持续性分化得到修复

▲ 作者：YEVGENIYA A. MIRONOVA, BRENDAN DANG, DONGEUN HEO, YU KANG T. XU, ANGELA YU-HUEY HSU, JAIME EUGENIN VON BERNHARDI, GIAN CARLO MOLINA-CASTRO, ANYA A. KIM, JING-PING LIN, AND DWIGHT E. BERGLES

▲链接：

https://www.science.org/doi/10.1126/science.adu2896

▲摘要：

少突胶质前体细胞（OPCs）是一种胶质祖细胞，负责分化为少突胶质细胞。这些细胞在学习过程中（适应性髓鞘形成）产生新的髓鞘，并在损伤或疾病导致髓鞘丢失后进行修复。作者研究了小鼠在正常发育、衰老过程中，以及脱髓鞘和炎症发生后，OPC的分化动态。

他们发现，在整个中枢神经系统中，无论髓鞘需求如何，OPCs始终以恒定速率持续尝试进行分化。此外，脱髓鞘并未改变OPC的分化速率，这表明OPC的分化是一种细胞自主性的过程。

▲ Abstract：

Oligodendrocyte precursor cells (OPCs) are glial progenitor cells responsible for differentiating into oligodendrocytes that produce new myelin during learning (adaptive myelination) and also regenerate myelin lost through injury or disease. Mironova et al. studied OPC differentiation dynamics in mice during normal development and aging, as well as after demyelination and inflammation. The authors showed that OPCs attempt to differentiate continuously throughout the central nervous system at a constant rate independently of myelin demand. Moreover, demyelination did not alter the OPC differentiation rate, indicating that OPC differentiation is cell autonomous.