Rigel, also known by its
Bayer designation Beta Orionis (ß Ori, ß Orionis), is the brightest star in the constellation
Orion and the
seventh brightest star in the night sky, with
visual magnitude 0.13. The star as seen from Earth is actually a triple star system, with the primary star (Rigel A) a blue-white supergiant of absolute magnitude -7.84 and around 120,000 times as luminous as the
Sun. It has exhausted its core hydrogen and swollen out to 79 times the Sun's radius. An
Alpha Cygni variable, it pulsates periodically. Visible in small telescopes and 500 times fainter than Rigel A, Rigel B is itself a
spectroscopic binary system, consisting of two
main sequence blue-white stars of spectral type B9V that are themselves estimated to be 2.5 and 1.9 times as massive as the Sun.