作者:李言 来源:科学网微信公众号 发布时间:2023/7/1 20:54:37
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《自然》(20230629出版)一周论文导读

 

Nature, 29 June 2023, Volume 618 Issue 7967

《自然》2023年6月29日,第618卷,7967期

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天文学Astronomy

A close-in giant planet escapes engulfment by its star

一颗逃脱了被恒星吞没命运的近距离巨行星

▲ 作者:Marc Hon, Daniel Huber, Nicholas Z. Rui et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06029-0

▲ 摘要:

在此,我们发现巨行星8 Ursae Minoris b围绕一个核心氦燃烧的红巨星旋转。这颗行星将在距离它的主恒星只有0.5天文单位的距离时被主恒星吞没,根据标准的单星演化预测,它的半径之前已经扩大到0.7天文单位。

考虑到燃烧氦的巨行星的寿命很短,且这颗行星的轨道近圆形,这与行星在最初远距离环绕的情况不一致。相反,这颗行星可能通过恒星合并避免了被吞没。这种合并可能改变了主恒星的演化情况,或使得8 Ursae Minoris b成为第二代行星。

这一系统表明,核心氦燃烧的红巨星可以包容近地行星,同时也为非标准恒星演化在晚期系外行星系统的生存中所起的作用提供了证据。

▲ Abstract:

Here we present the discovery that the giant planet 8 Ursae Minoris b orbits a core-helium-burning red giant. At a distance of only 0.5?AU from its host star, the planet would have been engulfed by its host star, which is predicted by standard single-star evolution to have previously expanded to a radius of 0.7?AU. Given the brief lifetime of helium-burning giants, the nearly circular orbit of the planet is challenging to reconcile with scenarios in which the planet survives by having a distant orbit initially. Instead, the planet may have avoided engulfment through a stellar merger that either altered the evolution of the host star or produced 8 Ursae Minoris b as a second-generation planet. This system shows that core-helium-burning red giants can harbour close planets and provides evidence for the role of non-canonical stellar evolution in the extended survival of late-stage exoplanetary systems.

物理学Physics

Magnetic-field-sensitive charge density waves in the superconductor UTe2

超导体UTe2中的磁场敏感电荷密度波

▲ 作者:Anuva Aishwarya, Julian May-Mann et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06005-8

▲ 摘要:

在此,我们使用扫描隧道显微镜揭示了重费米子三重态超导体UTe2中不寻常的电荷密度波(CDW)顺序。我们的高分辨率图揭示了一个多分量不相称的CDW,其强度随着场的增大而减弱,CDW最终在超导临界场Hc2下消失。

为了理解这种不寻常的电荷密度波现象,我们构建了一个基于Ginzburg-Landau理论的模型,该模型描述了均匀三重态超导体与三个三重态配对密度波态的共存。该理论预示了一种因起源于三重态配对密度波态、而对磁场敏感的子电荷密度波。这种理论也为我们的数据提供了可能的解释。

▲ Abstract:

Here we use scanning tunnelling microscopy to reveal an unusual charge-density-wave (CDW) order in the heavy-fermion triplet superconductor UTe2. Our high-resolution maps reveal a multi-component incommensurate CDW whose intensity gets weaker with increasing field, with the CDW eventually disappearing at the superconducting critical field Hc2. To understand the phenomenology of this unusual CDW, we construct a Ginzburg–Landau theory for a uniform triplet superconductor coexisting with three triplet pair-density-wave states. This theory gives rise to daughter CDWs that would be sensitive to magnetic field owing to their origin in a pair-density-wave state and provides a possible explanation for our data.

化学Chemistry

Chiral phonons in quartz probed by X-rays

用X射线探测石英中的手性声子

▲ 作者:Hiroki Ueda, Mirian García-Fernández et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06016-5

▲ 摘要:

在此,我们的实验证明了用圆偏振x射线的共振非弹性X射线散射可展示了手性声子。利用典型的手性材料石英,我们证明了固有手性的圆偏振X射线在倒易空间的特定位置与手性声子耦合,使得我们能确定晶格模式的手性色散。

我们对手性声子的实验证明证明了凝聚态物质的一种新自由,即非常重要,又为探索基于手性玻色子的新现象打开了大门。

▲ Abstract:

Here we show experimental proof of chiral phonons using resonant inelastic X-ray scattering with circularly polarized X-rays. Using the prototypical chiral material quartz, we demonstrate that circularly polarized X-rays, which are intrinsically chiral, couple to chiral phonons at specific positions in reciprocal space, allowing us to determine the chiral dispersion of the lattice modes. Our experimental proof of chiral phonons demonstrates a new degree of freedom in condensed matter that is both of fundamental importance and opens the door to exploration of new emergent phenomena based on chiral bosons.

大气科学Atmospheric Sciences

Natural short-lived halogens exert an indirect cooling effect on climate

天然的短寿命卤素对气候有间接的降温作用

▲ 作者:Alfonso Saiz-Lopez, Rafael P. Fernandez et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06119-z

▲ 摘要:

在此,我们展示了短寿命卤素对臭氧的辐射扰动(- 0.24±0.02瓦/平方米)产生了实质性的间接冷却效应(- 0.13±0.03瓦/平方米),由甲烷(+0.09±0.01瓦/平方米)、气溶胶(+0.03±0.01瓦/平方米)和平流层水蒸气(+0.011±0.001瓦/平方米)的辐射扰动补偿(+0.011±0.001瓦/平方米)。

重要的是,自1750年以来,由于自然卤素排放的人为增加,这种实质性的冷却效应上升了- 0.05±0.03瓦/平方米(61%),根据气候变暖预测和社会经济发展,预计未来将进一步变化(到2100年为18 - 31%)。我们总结到,短寿命卤素由于间接辐射效应,应该纳入气候模型,以提供一个更现实的地球气候系统的自然基线。

▲ Abstract:

Here we show that short-lived halogens exert a substantial indirect cooling effect at present (?0.13?±?0.03?watts per square metre) that arises from halogen-mediated radiative perturbations of ozone (?0.24?±?0.02?watts per square metre), compensated by those from methane (+0.09?±?0.01?watts per square metre), aerosols (+0.03?±?0.01?watts per square metre) and stratospheric water vapour (+0.011?±?0.001?watts per square metre). Importantly, this substantial cooling effect has increased since 1750 by ?0.05?±?0.03?watts per square metre (61?per cent), driven by the anthropogenic amplification of natural halogen emissions, and is projected to change further (18–31?per cent by 2100) depending on climate warming projections and socioeconomic development. We conclude that the indirect radiative effect due to short-lived halogens should now be incorporated into climate models to provide a more realistic natural baseline of Earth’s climate system.

地理学Geography

Uncovering the Ediacaran phosphorus cycle

揭秘埃迪卡拉纪磷循环

▲ 作者:Matthew S. Dodd, Wei Shi, Chao Li et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06077-6

▲ 摘要:

在此,我们使用来自全球分布的六个剖面的碳酸盐岩相关磷酸盐技术(CAP),重建与全球海洋氧合共同发生的大规模负碳同位素漂移Shuram漂移(SE)期间的海洋磷浓度。我们的研究数据表明,在Shuram漂移下降和上升期间,海洋磷浓度呈脉冲增长。

通过定量的生物地球化学模型,我们提出这一现象可以解释为主要由硫酸盐氧化的海洋有机物释放二氧化碳和磷,以及二氧化碳驱动的陆地风化进一步释放磷。总的来说,这可能导致有机黄铁矿埋藏和海洋氧化作用的增加。我们的CAP数据似乎也表明,在Shuram漂移沿海的最大和最小程度的海洋缺氧条件下,海洋磷浓度是相当的。

▲ Abstract:

Here we use carbonate-associated phosphate (CAP) from six globally distributed sections to reconstruct oceanic phosphorus concentrations during a large negative carbon-isotope excursion—the Shuram excursion (SE)—which co-occurred with global oceanic oxygenation. Our data suggest pulsed increases in oceanic phosphorus concentrations during the falling and rising limbs of the SE. Using a quantitative biogeochemical model, we propose that this observation could be explained by carbon dioxide and phosphorus release from marine organic-matter oxidation primarily by sulfate, with further phosphorus release from carbon-dioxide-driven weathering on land. Collectively, this may have resulted in elevated organic-pyrite burial and ocean oxygenation. Our CAP data also seem to suggest equivalent oceanic phosphorus concentrations under maximum and minimum extents of ocean anoxia across the SE.

Microbial carbon use efficiency promotes global soil carbon storage

微生物碳利用效率提高全球土壤碳储量

▲ 作者:Feng Tao, Yuanyuan Huang et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06042-3

▲ 摘要:

在此,我们采用全球尺度数据集、微生物过程显式模型、数据同化、深度学习和元分析相结合的方法,研究了微生物碳利用效率(CUE)与土壤有机碳保存之间的关系,以及与气候、植被和土壤性质的相互作用。我们发现,在决定全球碳储量及其空间变化方面,CUE的重要性至少是其他评估因素(如碳输入、分解或垂直运输)的4倍。

CUE与土壤有机碳含量呈显著正相关。我们的研究结果表明,CUE是全球土壤有机碳储存的主要决定因素。了解CUE背后的微生物过程及其对环境的依赖性,有助于预测土壤有机碳对气候变化的反馈。

▲ Abstract:

Here we examine the relationship between CUE and the preservation of SOC, and interactions with climate, vegetation and edaphic properties, using a combination of global-scale datasets, a microbial-process explicit model, data assimilation, deep learning and meta-analysis. We find that CUE is at least four times as important as other evaluated factors, such as carbon input, decomposition or vertical transport, in determining SOC storage and its spatial variation across the globe. In addition, CUE shows a positive correlation with SOC content. Our findings point to microbial CUE as a major determinant of global SOC storage. Understanding the microbial processes underlying CUE and their environmental dependence may help the prediction of SOC feedback to a changing climate.

 
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