Үлкен Аюдың Құйрықшасындағы Екі Жұлдыз: Мизар мен Алькор

Binary Stars in the Big Dipper asterism

Mizar and Alcor are two stars forming a naked eye double in the handle of the Big Dipper (or Plough) asterism in the constellation of Ursa Major. Mizar consists of two stars with magnitudes 2.2 and 3.9 that can be seen easily without the aid of a telescope. Mizar's star is not a double star, but a four star binary system located in the constellation Ursa Major (also known as the Big Dipper). This system consists of two pairs of double stars that are gravitationally bound to each other. Mizar is the second star from the end of the Big Dipper's handle, and Alcor its fainter companion. The traditional name Mizar derives from the Arabic المئزر miʼzar meaning 'apron; wrapper, covering, cover'. Alcor was originally Arabic سها Suhā/Sohā, meaning either the ‘forgotten’ or ‘neglected’ one; notable as a faintly perceptible companion of Mizar. Mizar, also designated Zeta Ursae Majoris (ζ Ursae Majoris, abbreviated Zeta UMa, ζ UMa), is itself a quadruple system and Alcor, also designated 80 Ursae Majoris (80 UMa), is a binary, the pair together forming a sextuple system. In fact, it was the first known binary star system, discovered by Italian astronomer Giovanni Battista Riccioli in 1650. The whole system lies about 83 light years away from the Sun, as measured by the Hipparcos astrometry satellite.

With normal eyesight Alcor appears at about 12 minutes of arc from Mizar. Alcor is of magnitude 3.99 and spectral class A5V. It has a faint red dwarf companion separated by 1 second of arc. Between Mizar and Alcor, the 8th magnitude star Sidus Ludoviciana is a distant background object.

Mizar is known as Vasishtha, one of the Saptarishi, and Alcor as Arundhati, wife of Vasishtha, in Indian astronomy. As a married couple, they are considered to symbolize marriage and in some Hindu communities to this day priests conducting a wedding ceremony allude to or point out the asterism as a symbol of the closeness marriage brings to a couple. Al Sahja was the rhythmical form of the usual Suha. It appears as الخوّار , 'the Faint One', in an interesting list of Arabic star names, published in Popular Astronomy, January 1895, by Professor Robert H. West, of the Syrian Protestant College at Beirut. Although the statement has been made that Alcor was not known to the ancient Greeks, there is an old story that it was the Lost Pleiad Electra, which had wandered here from her companions and became Alopex, the Fox. A Latin title was Eques Stellula, the Little Starry Horseman; Eques, the Cavalier, is from the 17th century German astronomer Bayer. Mizar and Alcor together are sometimes called the "Horse and Rider" (and popularly, in England, Jack on the Middle Horse), with Mizar being the horse. The Persian astronomer Al Biruni (973–1048 AD) mentioned its importance in the family life of the Arabs on the 18th day of the Syrian month Adar, the March equinox; and a modern story of that same people makes it the infant of the walidan (mother?) among the three Banat (the Mourners: Alioth, Mizar, and Alkaid). Chinese Taoism personifies ζ Ursae Majoris as the Lu star. In Chinese, 北斗 (Běi Dǒu), meaning Northern Dipper, refers to an asterism consisting of Zeta Ursae Majoris, Alpha Ursae Majoris, Beta Ursae Majoris, Gamma Ursae Majoris, Delta Ursae Majoris, Epsilon Ursae Majoris and Eta Ursae Majoris. Consequently, Zeta Ursae Majoris itself is known as 北斗六 Běi Dǒu liù, and 開陽 Kāi Yáng,
Mizar is Chickadee and Alcor is his cooking pot in the Mi'kmaq myth of the great bear and the seven hunters.

Benedetto Castelli, one of Galileo's colleagues in the 17th century, observed Mizar through a telescope and realized that it was a binary system: Mizar A and Mizar B. Then, throughout the 19th century and the beginning of the 20th century, with the help of spectroscopy, scientists showed that Mizar A and B were both binary systems. In 1908, the Alcor Mizar system was the first apparent 5 star system ever discovered. In 2009, Eric Mamajek and his colleagues from the University of Rochester, while searching for exoplanets, discovered that Alcor was also a binary system, making the Alcor and Mizar a 6 star system. The same conclusion was independently found by Ben Oppenheimer from the American Natural History Museum.