Three-dimensional imaging of convective cells in the photosphere of Betelgeuse

Abstract

Understanding convection in red supergiants and the mechanisms that trigger the mass loss from these evolved stars are the general goals of most observations of Betelgeuse and its inner circumstellar environment. Linear spectropolarimetry of the atomic lines of the spectrum of Betelgeuse reveals information about the three-dimensional (3D) distribution of brightness in its atmosphere. We model the distribution of plasma and its velocities and use inversion algorithms to fit the observed linear polarization. We obtain the first 3D images of the photosphere of Betelgeuse. Within the limits of the used approximations, we recover vertical convective flows and measure the velocity of the rising plasma at different heights in the photosphere. In several cases, we find this velocity to be constant with height, indicating the presence of forces other than gravity acting on the plasma and counteracting it. In some cases, these forces are sufficient to maintain plasma rising at 60\,\kms to heights where this velocity is comparable to the escape velocity. Forces are present in the photosphere of Betelgeuse that allow plasma to reach velocities close to the escape velocity. These mechanisms may suffice to trigger mass loss and sustain the observed large stellar winds of these evolved stars.

arXiv comment15 pages, 10 figures. In press with A&A

References in corpus (15)

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• A BCool survey of stellar magnetic cycles
• The Great Dimming of Betelgeuse: the photosphere as revealed by tomography over the past 15 years
• The effect of winds on atmospheric layers of red supergiants I. Modelling for interferometric observations
• A Non-Detection of Red Supergiant Convection in Gaia
• Spectroscopic detection of Altair's non-radial pulsations
• The height of convective plumes in the red supergiant $\mu$ Cep
• Betelgeuse, the Prototypical Red Supergiant
• A Multi-Year Photopolarimetric Study of the Semi-Regular Variable V CVn and Identification of Analogue Sources
• The variability of Betelgeuse explained by surface convection
• Making sense of the spectral line profiles of Betelgeuse and other Red SuperGiants
• The Red and Yellow Hypergiants
• Confirming the Magnetic Field Detection at the Surface of $\chi$ Cyg
• First images of Antares photosphere from spectropolarimetry