Beta Cephei (β Cep / β Cephei) is a star in the constellationCepheus. It also has the traditional name Alfirk. The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Cepheus is a northern constellation named after King Cepheus in Greek mythology, and is considered to represent a king. ...
Beta Cephei is the prototype of the Beta Cephei variable stars. Its magnitude varies between +3.15 and +3.21 with a period of 0.1904844 days. It belongs to the spig yelow bitchpectral class B1 and is 230 light years from Earth. Beta Cephei variables are variable stars which exhibit variations in their brightness due to pulsations of the stars surfaces. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Earth, also known as Terra, and Tellus mostly in the 19th century, is the third-closest planet to the Sun. ...
Like all BetaCepheistars, however, Alfirk pulsates with many periods at once, smaller changes taking place with a variety of other periods between four and five hours, in addition to 6- and 12-day rotational modulations.
BetaCephei has a hot corona that radiates about 2,000 times more X-ray power than the Sun – activity thought to be related to the star's advanced stage of evolution.
Two smaller, dimmer A stars accompany it: the inner, about 45 AU away with an orbital period of some 90 years; the outer, easily seen in a small telescope, at least 2,400 AU away with a period of at least 30,000 years.
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