galaxy in the constellation Ursa Major From Wikipedia, the free encyclopedia
Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a spiral galaxy. It is in the constellation Ursa Major. It is large. It is about 12 million light-years from Earth. It has an active galactic nucleus (which has a supermassive black hole). For these reasons Messier 81 has been well studied by professional astronomers. The galaxy is large and very bright. This makes it a popular object for amateur astronomers to look at.[1]
Messier 81 was discovered by Johann Elert Bode in 1774.[2] The galaxy is sometimes called "Bode's Galaxy". In 1779, Pierre Méchain and Charles Messier reidentified Bode's object. They listed it as Messier 81 in the Messier Catalogue.[2]
M81 is dusty. Interstellar dust is found in the galaxy's spiral arms. It is connected with star formation areas.[3][4] The hot blue stars in star formation areas heat the dust and the hot dust emits infrared energy from these areas.
Only one supernova has been seen in Messier 81.[5] The supernova is named SN 1993J. It was discovered on 28 March 1993 by F. Garcia in Spain.[6] At the time, it was the second brightest supernova seen in the 20th century.[7]
Messier 81 is the largest galaxy in the M81 Group. The M81 Group is a group of 34 galaxies in the constellation Ursa Major.[8] This Group and the Local Group, containing the Milky Way,[8] are close together in the Virgo Supercluster.
Messier 81 is about 10° northwest of Alpha Ursae Majoris.[1][9] Messier 81 and Messier 82 can both be easily seen using binoculars and small telescopes.[1]
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