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The pink arrow at the star on left labelled α indicates Betelgeuse in Orion

Betelgeuse, also designated Alpha Orionis (α Orionis, abbreviated Alpha Ori, α Ori), is a large red supergiant star in the constellation Orion. It is the ninth-brightest star in the night sky, and second-brightest in Orion. If humans could see all types of light, Betelgeuse would be the brightest star. It would be even brighter than Sirius.

Betelgeuse is a semiregular variable star whose apparent magnitude varies between 0.2 and 1.2.[1] This is the widest range of any first-magnitude star. It is also one of the largest and most luminous observable stars, with a radius between 950 to 1,000 times wider than the sun's, the same as 1.322 to 1.392 billion kilometers in diameter. Betelgeuse was the first star other than the Sun whose size was known. The star's distance from Earth was estimated in 2008 at 640 light-years, with a mean absolute magnitude of about −6.02.[2]

Less than 10 million years old, Betelgeuse has evolved rapidly because of its high mass.[3] It is moving through the interstellar medium at a supersonic speed of 30 km/s, creating a shock wave over 4 light-years wide.

Betelgeuse is in a late stage of stellar evolution. It will rapidly go through its life cycle before exploding as a type II supernova sometime in the next million years. An observation by the Herschel Space Observatory in January 2013 showed that the star's winds are crashing against the surrounding interstellar medium.[4]

Betelgeuse is one of the very red supergiant stars to have a bow shock, the others being Mu Cephei and IRC-10414.

Related pages[change | change source]

References[change | change source]

  1. Davis, Kate (AAVSO Technical Assistant, Web) 2000. Variable star of the month: Alpha Orionis. American Association of Variable Star Observers (AAVSO). [1]
  2. Harper, Graham M. et al. 2008. A new VLA-Hipparcos distance to Betelgeuse and its implications. The Astronomical Journal 135 (4): 1430–40. [2]
  3. Levesque E.M. 2010. The physical properties of red supergiants. Astronomical Society of the Pacific. 425 Hot and Cool: Bridging Gaps in Massive Star Evolution ASP Conference Series: 103. [3]
  4. "Betelgeuse braces for a collision". ESA. 2013-01-22. Retrieved 2013-01-23.