The non-uniform, dynamic atmosphere of Betelgeuse observed at mid-infrared wavelengths

TL;DR

This study uses mid-infrared interferometry to analyze Betelgeuse's dynamic atmosphere, revealing a non-uniform, variable layer within 1.4 stellar radii influenced by convection and contributing to mass loss.

Contribution

First detailed interferometric analysis of Betelgeuse's inner atmosphere at 11.15 microns across multiple years, showing variability and non-uniformity.

Findings

Optically thick layer within 1.4 stellar radii with variable temperature and size.

Layer's opacity significantly influenced by electron-hydrogen collisions.

Surface convective activity impacts atmospheric dynamics and mass-loss processes.

Abstract

We present an interferometric study of the continuum surface of the red supergiant star Betelgeuse at 11.15 microns wavelength, using data obtained with the Berkeley Infrared Spatial Interferometer each year between 2006 and 2010. These data allow an investigation of an optically thick layer within 1.4 stellar radii of the photosphere. The layer has an optical depth of ~1 at 11.15 microns, and varies in temperature between 1900 K and 2800 K and in outer radius between 1.16 and 1.36 stellar radii. Electron-hydrogen atom collisions contribute significantly to the opacity of the layer. The layer has a non-uniform intensity distribution that changes between observing epochs. These results indicate that large-scale surface convective activity strongly influences the dynamics of the inner atmosphere of Betelgeuse, and mass-loss processes.