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[[Image:Position_Alpha_Ori.png|thumb|right|196px|Position and location of Betelgeuse as shown by the pink arrow]]

'''Betelgeuse''', or '''Alpha Orionis''' is the second brightest star located in the northeast part the constellation [[Orion]] and the ninth brightest star in the night sky. The name Betelgeuse itself is a corruption of the Arabic يد الجوزاء yad al-jawzā ("hand of the central one")<ref>Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning (Revised ed.). New York: Dover Publications. ISBN 0486210790.</ref>. The star has many names throughout the world including ''Ardra'' in Hindi, and ''Shēnsùsì'' (参宿四, the Fourth Star of the Constellation of Three Stars), in Chinese.

| image          =Position_Alpha_Ori.png

| designation    =Alpha Orionis

| rightascension  =05^h 55^m 10.3053^s

| declination    =+07^o 24′ 25.426

| type            =[[Supergiant]] [[star]]  

 

'''Betelgeuse''', or '''Alpha Orionis''' is an orange-reddish star located in the northeast part the constellation [[Orion]].  The star is typically the second brightest in the [[constellation]], although as a [[variable star]], its apparent magnitude can exceed from time to time, that of [[Rigel]], normally the brightest star of Orion.

 

The name Betelgeuse itself is a corruption of the Arabic يد الجوزاء ''yad al-jawzā'' ("hand of the central one").  Other names various Arabic authors have given the star are ''Al Mankib'', (the Shoulder); ''Al Dhira'', (the Arm); and ''Al Yad al Yamma'', (the Right Hand). As one of the most recognizable stars in the night sky, it has many other names throughout the world including ''Ardra'' in [[Hindi]], ''Klaria'', meaning an Armlet in [[Coptic]], ''Bašn'' meaning the Arm in [[Persian]], and ''Shēnsùsì'' (参宿四, the Fourth Star of the Constellation of Three Stars), in [[Chinese]].<ref>http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Orion*.html</ref>

===The Star===

===The Star===

Betelgeuse is the 11th brightest star in the night sky, easily seen by human eyes with an apparent magnitude of 0.58, appearing with an orange-like color.  In addition it is a luminous red supergiant, with spectral and luminosity type M1-2 Ib. As one of the largest star's known, Betelgeuse has between 12 and 17 times our star's mass, over 650 times its diameter, and estimated to be 9,400 times as luminous as the sun.  If Betelgeuse was the central star of our solar system, it may well extend out to between the orbits of Mara and Jupiter<ref>http://www.solstation.com/x-objects/betelgeuse.htm</ref>.  The star is estimated to be around 640 light-years from Sol<ref name="Bettle">http://www.astro.illinois.edu/~jkaler/sow/betelgeuse.html</ref>.

Betelgeuse is a luminous red [[supergiant]] of spectral and luminosity type M1-2 Ib, with a surface temperature of around 3650 K.  The star has an "average" apparent magnitude of 0.58 in the night sky, making it the 9th brightest star.<ref>http://simbad.u-strasbg.fr/simbad/sim-id?Ident=betelgeuse</ref> The star though is a [[variable star]] where the magnitude varies between 0.3 and 1.1 over multiple periods in a cycle of variability that follow no particular length of time (although typically between a half of a year and six years).

 

One area of debate is the distance of the star.  Using the most recent and modern direct [[parallax]] measurements resulted in a distance of 495 light years.  However, using the star's natural radio emissions for parallax yields a distance of 640 light years.  Allowing for the high amount of [[infrared]] [[radiation]] emitted from the star and the absorption of light by its circumstellar dust disk, a compromise distance of 570 light years is most often used.<ref name="Bettle">http://stars.astro.illinois.edu/sow/betelgeuse.html</ref>

 

At the compromise distance of 570 light years, the star has a total bolometric luminosity some 85,000 times that of the [[Sun]].  Because Betelgeuse is so immense in size, it is easy to measure its angular diameter, which is 0.054 seconds of arc. This places the radius of the star at some 3.6 AU, or as great as that of the [[asteroid belt]] (with a total diameter of 7.2 AU).<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1992MNRAS.257..369W</ref> Measuring the star in [[ultraviolet]] light has suggested its radius is over 8 AU in size, more than twice the distance found at optical wavelengths.<ref>http://www.cfa.harvard.edu/news/archive/betel97.html</ref>

===Future Supernova===

===Future Supernova===

Astronomers believe that much like many of the other stars in the [[Orion]] constellation, Belegeuse is only a few million years old, and formed from molecular clouds observed in Orion.  Due to its extremely high mass though, the star has evolved quickly, and many astronomers have concluded that Betelgeuse will become a [[supernova]], which if happened would outshine the full moon<ref name="Bettle">http://www.astro.illinois.edu/~jkaler/sow/betelgeuse.html</ref>.

Astronomers believe that much like many of the other stars in the [[Orion]] constellation, Betelgeuse is only a few million years old, and formed from molecular clouds observed in [[Orion_nebula|Orion]].  Due to its extremely high mass though, the star has evolved quickly and has already consumed the [[hydrogen]] in its core for thermonuclear fusion.  The star is fusing core [[helium]] into [[carbon]] and [[oxygen]], which has swelled the outer layers of gas in the star, causing its great size.  Eventually the star will fuse heavier elements all the way to [[iron]] before collapsing into a [[supernova]].<ref>http://books.google.com/books?id=Aq24O7B4ehoC&dq=the+hundred+greatest+stars&printsec=frontcover&source=bn&hl=en&ei=PNMnS5-BHI3anAeqsLm1DQ&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBwQ6AEwAw#v=onepage&q=Betelgeuse&f=false</ref>  Such an explosion would be so bright, it would outshine the full [[moon]].<ref name="Bettle">http://stars.astro.illinois.edu/sow/betelgeuse.html</ref>.

The [[UC Berkeley|UC Berkeley's]] Infrared Spatial Interferometer (ISI) atop [[Mt. Wilson Observatory]] in Southern [[California]] collected evidence over 15 consecutive years, showing the star is constantly contracting<ref>http://esciencenews.com/articles/2009/06/09/red.giant.star.betelgeuse.mysteriously.shrinking</ref>.  The star is estimated to have shrunk 15 percent in size since 1993 and the rate of contraction is increasing, the total observed contraction is equal to half an astronomical unit, or equivalent of the distance of Venus from the sun<ref>http://www.berkeley.edu/news/media/releases/2009/06/09_betelim.shtml</ref>.  It is speculated this is the behavior expected for a star that has reached the end of its life and the beginning of gravitational collapse.  because of the mass of Betelgeuse, the result of a supernova explosion will be either a [[neutron star]] or even a [[black hole]].

The [[UC Berkeley|UC Berkeley's]] Infrared Spatial Interferometer (ISI) atop [[Mt. Wilson Observatory]] in Southern [[California]] collected evidence over 15 consecutive years, showing the star is constantly contracting<ref>http://esciencenews.com/articles/2009/06/09/red.giant.star.betelgeuse.mysteriously.shrinking</ref>.  The star is estimated to have shrunk 15 percent in size since 1993 and the rate of contraction is increasing, the total observed contraction is equal to half an astronomical unit, or equivalent of the distance of Venus from the sun<ref>http://www.berkeley.edu/news/media/releases/2009/06/09_betelim.shtml</ref>.  It is speculated this is the behavior expected for a star that has reached the end of its life and the beginning of gravitational collapse.  Because of the mass of Betelgeuse, the result of the supernova explosion will be either a [[neutron star]] or even a [[black hole]].

Updated high resolutions images of Betelgeuse obtained by the [[Very Large Telescope]] in [[Chile]] in July 2009, revealed new evidence that Betelgeuse is rapidly shedding mass.  A large gas plume is shown to be surrounding the star.<ref>http://www.eso.org/gallery/v/ESOPIA/Stars/phot-27b-09-fullres.tif.html</ref>  If the plume was in our solar system, it would extend to the orbit of [[Jupiter]].  The plume is viewed as further evidence by scientists the star is very near the end of its life.<ref>http://antwrp.gsfc.nasa.gov/apod/ap090805.html</ref>

Updated high resolutions images of Betelgeuse obtained by the [[Very Large Telescope]] in [[Chile]] in July 2009, revealed new evidence that Betelgeuse is rapidly shedding mass.  A large gas plume is shown to be surrounding the star.<ref>http://www.eso.org/gallery/v/ESOPIA/Stars/phot-27b-09-fullres.tif.html</ref>  If the plume was in our solar system, it would extend to the orbit of [[Jupiter]].  The plume is viewed as further evidence by scientists the star is very near the end of its life.<ref>http://antwrp.gsfc.nasa.gov/apod/ap090805.html</ref>