Imaging Stellar Atmospheres

Direct imaging of the photospheres of stars other than the Sun remains beyond the scope of current optical telescopes, with the exception of this Hubble Space Telescope image of the red supergiant Betelgeuse, in the constellation of Orion. The image shows clearly a variation in the colour, and hence the surface temperature, of the photosphere. The bright "spot" on the surface of Betelgeuse may be associated with the turbulent transport of hot gas from the heart of the star to the surface, as Betelgeuse approaches the end of its life. Gravitational lensing offers a unique opportunity to deduce the presence of similar "hotspots" on the photospheres of other red giant stars similar to Betelgeuse.