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

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 for the production of 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 disc 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 disc is $0.72\pm 0.05$ astronomical units (au). We measure the velocity of the surface motions to vary between $-18$ and $+20$ km s${}^{-1}$, which means the convective timescale is approximately one month. This indicates a possible difference between the convection properties of low-mass and high-mass evolved stars.

This version of the article has been accepted for publication in Nature, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at http://dx.doi.org/10.1038/s41586-024-07836-9

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Cited by in corpus (6)

• ATOMIUM: Continuum emission and evidence of dust enhancement from binary motion
• Probing the Extended Atmospheres of AGB Stars: I. Synthetic imaging of 1D hydrodynamical models at radio and (sub-)millimeter wavelengths
• High-angular-resolution ALMA imaging of the inhomogeneous dynamical atmosphere of the asymptotic giant branch star W Hya
• Inferring hemispheric asymmetries of stellar active regions through the information content of astrometric signals
• X TrA through the eyes of MATISSE: More evidence of clumpy molecular layers around C-type asymptotic giant branch stars
• VLTI-GRAVITY measurements of cool evolved stars: II. Pulsation properties and mass-loss process of the Mira star R Car and the red supergiant VX Sgr