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

• 成果类型: Article
• 署名作者: Vlemmings, Wouter; Khouri, Theo; Arbab, Behzad Bojnordi; De Beck, Elvire; Maercker, Matthias
• 署名单位: Chalmers University of Technology
• 刊物名称: Nature
• ISSN/ISSBN: 0028-3909
• DOI: 10.1038/s41586-024-07836-9
• 发表日期: 2024-09-12
• 关键词: galactic neutral hydrogen; power spectrum; granulation; emission; scale

摘要

The transport of energy through convection is important during many stages of stellar evolution1,2, and is best studied in our Sun3 or giant evolved stars4. Features that are attributed to convection are found on the surface of massive red supergiant stars5-8. Also for lower-mass evolved stars, indications of convection are found9-13, 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 medium14. 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. Presenting a series of interferometric images of R Doradus, this study reveals prominent convective structures on the surface of this giant evolved star that have a timescale of about one month.