Betelgeuse and nebulae. Betelgeuse (centre) is a red supergiant star in the constellation Orion. Three red emission nebulae are seen around the star; Barnard's Loop nebula (left), Lambda Orionis nebula (bottom) and the Rosette nebula (top right corner). An emission nebula is a huge cloud of gas and dust that glows as the hydrogen it contains is ionised by radiation from the hot young stars that have formed within it. A bell-shaped dark ring is seen surrounding Betelgeuse. Captured from Cumeada Observatory, Reguengos de Monsaraz, Portugal.