近日，瑞典查尔姆斯理工大学的Wouter Vlemmings及其研究团队取得一项新进展。经过不懈努力，他们对巨大演化行星表面上一个月的对流时间尺度进行研究。相关研究成果已于2024年9月11日在国际权威学术期刊《自然》上发表。

本研究报道了一系列关于演化后巨大行星RDoradus表面的重建干涉图像。这些图像揭示了一个恒星盘，其上具有显著的小尺度特征，这些特征展示了恒星表面的对流结构和运动。研究人员发现，恒星盘上特征的主导结构尺度为0.72±0.05天文单位。研究人员测得表面运动速度在-18至+20公里/秒之间变化，这意味着对流的时间尺度约为一个月。这表明低质量和高质量演化后恒星的对流特性可能存在差异。

据悉，对流在恒星演化的许多阶段中对于能量的输运至关重要，而在太阳或巨大的演化后恒星中对其进行研究最为适宜。在质量巨大的红超巨星表面，可观察到归因于对流的特征。在质量较小的演化后恒星中，也发现了对流的迹象，但对流的时间和尺度仍缺乏明确的界定。模型表明，对流运动对于产生强风至关重要，这些强风将恒星核合成的产物送回星际介质中。

附：英文原文

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

Author: Vlemmings, Wouter, Khouri, Theo, Bojnordi Arbab, Behzad, De Beck, Elvire, Maercker, Matthias

Issue&Volume: 2024-09-11

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 RDoradus. 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 +20kms^-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.

DOI: 10.1038/s41586-024-07836-9

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