Betelgeuse bēt´əljo͞oz˝ [key], bright star in the constellation Orion ; Bayer designation α Orionis; 1992 position R.A. 5 h54.8 m, Dec. +7°24′. A red supergiant with a luminosity about 13,000 times that of the sun, it is of spectral class M2 Iab. Betelgeuse is a semiregular variable star with apparent magnitude ranging from 0.06 to 0.75; thus, at maximum brightness it is one of the 10 brightest stars in the sky. Betelgeuse marks the right shoulder of Orion; its distance is about 500 light-years.
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