《自然》（20240912出版）一周论文导读

 
《自然》（20240912出版）一周论文导读  
 

 

编译|冯维维

Nature,12 September 2024, Volume 633 Issue 8029

《自然》，2024年9月12日，第633卷，8029期

物理学Physics

One month convection timescale on the surface of a giant evolved star

演化巨恒星表面对流时间尺度为1个月

▲ 作者：Wouter Vlemmings, Theo Khouri, Behzad Bojnordi Arbab, Elvire De Beck & Matthias Maercker

▲ 链接：

https://www.nature.com/articles/s41586-024-07836-9

▲ 摘要：

在恒星演化的许多阶段，能量的对流传输都很重要，这在太阳或巨大的演化恒星中已经得到了很好的研究。在大质量红超巨星的表面也发现了对流的特征。同样，对于低质量演化的恒星，也发现了对流的迹象，但对流的时间尺度和大小仍然没有得到很好的限制。

模型表明，对流运动对于产生强风至关重要，强风使恒星核合成的产物返回到星际介质中。研究者报告了一系列重建的干涉测量图像的表面演变的巨星R剑鱼座。这些图像揭示了一个具有突出的小尺度特征的星盘，它提供了恒星表面对流的结构和运动。

他们发现恒星盘上特征的主导结构尺寸为0.72±0.05天文单位。他们测量到地表运动的速度在- 18和+20 km s - 1之间变化，这意味着对流的时间尺度大约是一个月。这表明低质量和高质量演化恒星的对流特性之间可能存在差异。

▲ Abstract：

The transport of energy through convection is important during many stages of stellar evolution, and is best studied in our Sun or giant evolved stars. Features that are attributed to convection are found on the surface of massive red supergiant stars. Also for lower-mass evolved stars, indications of convection are found, but convective timescales and sizes remain poorly constrained. Models indicate that convective motions are crucial to produce strong winds that return the products of stellar nucleosynthesis into the interstellar medium. Here we report a series of reconstructed interferometric images of the surface of the evolved giant star R?Doradus. The images reveal a stellar disk with prominent small-scale features that provide the structure and motions of convection on the stellar surface. We find that the dominant structure size of the features on the stellar disk is 0.72?±?0.05 astronomical units. We measure the velocity of the surface motions to vary between ?18 and +20?km?s?1, which means that the convective timescale is approximately one month. This indicates a possible difference between the convection properties of low-mass and high-mass evolved stars.

Spectroscopic confirmation of two luminous galaxies at a redshift of 14

两个红移为14的发光星系

▲ 作者：Stefano Carniani, Kevin Hainline, Francesco D’Eugenio, Daniel J. Eisenstein, Peter Jakobsen, Joris Witstok, Benjamin D. Johnson, Jacopo Chevallard, Roberto Maiolino, Jakob M. Helton, Chris Willott, Brant Robertson, Stacey Alberts, Santiago Arribas, William M. Baker, Rachana Bhatawdekar, Kristan Boyett, Andrew J. Bunker, Alex J. Cameron, Phillip A. Cargile, Stéphane Charlot, Mirko Curti, Emma Curtis-Lake, Eiichi Egami, Christopher N. A. Willmer Show authors

▲ 链接：

https://www.nature.com/articles/s41586-024-07860-9

▲ 摘要：

詹姆斯·韦布太空望远镜首次观测的红移为z≈13的星系，彻底改变了人们对宇宙的理解。此外，“黎明”号探测器发现的许多发光星系（z >10）表明，星系发展迅速，与许多标准模型存在明显的张力。然而，这些星系大多缺乏光谱确认，因此它们的距离和性质是不确定的。

研究者展示了韦布先进深河外巡天—近红外光谱仪对两个发光星系在和z = 13.90±0.17处的光谱确认。光谱显示紫外连续带明显的莱曼α断裂，但没有探测到发射线。