Alpha Trianguli (α Tri / α Trianguli) is a binary star in the constellation Triangulum. It also has the traditional names Metallah or Ras al Muthallah, and Caput Trianguli which derive from phrases meaning "the head of the triangle". In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... Jump to: navigation, search The J2000. ... Jump to: navigation, search Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Triangulum is a small northern constellation whose three brightest stars, of third and fourth magnitude, form an elongated triangle. ... 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. ... Jump to: navigation, search 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 binary star system consists of two stars both orbiting around their barycenter. ... Jump to: navigation, search Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Triangulum is a small northern constellation whose three brightest stars, of third and fourth magnitude, form an elongated triangle. ...

Alpha Trianguli is a yellow-white F-type subgiant with a mean apparent magnitude of +3.42. Its mass is about 1.5 times that of the Sun and its diameter is about 3 times as large as the Sun's. 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. ... Subgiant star is a class of stars that are brighter than normal main sequence (dwarf) stars, but not as bright as true giant stars. ... 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. ...

Metallah is a spectroscopic binary whose components have an orbital period of only 1.74 days. The companion star is a mere 6 million km (3.7 million miles) from the main star. The whole system is approximately 64.1 light years from Earth. A spectroscopic binary star is a binary star which cannot be resolved as a visual binary, even with telescopes of the highest existing resolving power. ... A kilometre (American spelling: kilometer) (symbol: km) is a unit of length equal to 1000 metres (from the Greek words khilia = thousand and metro = count/measure). ... A mile is any of several units of distance, or, in physics terminology, of length. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Jump to: navigation, search Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ...

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• Alpha Tri