High-resolution imaging of Betelgeuse and Mira

Abstract

Diffraction-limited images have been made of the M giant stars α Orionis (Betelgeuse) and ο Ceti (Mira), using the non-redundant masking method at the 4.2-m William Herschel Telescope, for wavelengths between 546 and 710 nm. The brightness distribution for the surface of Betelgeuse is non-uniform, and has shown large changes over a period of 22 months. The disc of Mira is significantly elongated along position angle 120°, and there is evidence that the radial intensity profile is approximately Gaussian.