Betelgeuse red supergiant star. Animation of the location in the night sky and the properties of the M-type star Betelgeuse (Alpha Orionis), in the constellation Orion. Betelgeuse is a red supergiant star, 1180 times wider than the Sun (over 1.6 billion kilometres across) and 12 times its mass. Less than 10 million years old, Betelgeuse has evolved rapidly because of its high mass. It is in a late stage of stellar evolution, expected to explode as a type II supernova within the next million years. Betelgeuse is spectral type M2, with a luminosity class of Iab. It is some 90, 000-150, 000 times more luminous than the Sun and has an atmospheric temperature of 3140-3640 Kelvin. Its spectrum includes strong titanium oxide lines and some calcium lines.