Alcyone (η Tau / η Tauri / Eta Tauri) is a star system in the constellation Taurus. It is the brightest star in the Pleiades open cluster. Alcyone is approximately 440 light years from Earth. In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... The J2000. ... -1... Taurus (♉) is one of the constellations of the zodiac, and its name is Latin for Bull. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... A star system or stellar system is a group of stars (and possibly smaller bodies such as planets or asteroids) that orbit one another (a system with planetary bodies orbiting stars, are referred to as solar systems or planetary systems). ... -1... Taurus (♉) is one of the constellations of the zodiac, and its name is Latin for Bull. ... The Pleiades, dominated by hot blue stars surrounded by reflection nebulosity The Pleiades (pleye-a-deez or plee-a-deez, also known as M45, or the Seven Sisters) is an open cluster in the constellation of Taurus. ... An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud, and are still gravitationally bound to each other. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ...

The primary component, Alcyone A, is a blue-white B-type giant with an apparent magnitude of +2.85. It is an eclipsing binary, and the two components have a separation of 0.031 arcseconds, or about the distance from the Sun to Jupiter. In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... According to the Hertzsprung-Russell diagram, a red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giants. Examples include Aldebaran and Arcturus. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... An eclipsing binary star is a binary star in which the orbit plane of the two stars lies so nearly in the line of sight of the observer that the components undergo mutual eclipses. ... A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. ... The Sun is the star at the centre of our Solar system. ... Genitive Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ...

The binary star is orbited by three more companions. Alcyone B and Alcyone C are both 8th magnitude white A-type dwarfs and are separated from A by 117 and 181 arcseconds respectively. Alcyone D is a yellow-white F-type dwarf, 191 arcseconds from the primary. It has an apparent magnitude of +8.7. Alcyone C is classified as a Delta Scuti type variable star and it's brightness varies from magnitude +8.25 to +8.30 over 1.13 hours. In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... Most stars are of nearly constant luminosity. ...