Beta Centauri

β Centauri
Observation data
Epoch J2000
ConstellationCentaurus
Right ascension14h 03m 49.4s
Declination−60° 22′ 23″
Apparent magnitude (V)0.60
Characteristics
Spectral typeB1III
U-B color index−0.98
B-V color index−0.22
Variable typeβ Cep
Astrometry
Radial velocity (Rv)5.9 km/s
Proper motion (μ) RA: −33.96 mas/yr
Dec.: −2.506 mas/yr
Parallax (π)6.21  0.56 mas
Distance0 ± 0 ly
(0 ± 0 pc)
Absolute magnitude (MV)−5.42
Details
Mass12 M
Luminosity11200 | L
Other designations
Agena, Hadar, Khadar, HR 5267, HD 122451, CD−59°5365, LHS 51, SAO 252582, HIP 68702, GC 18971, CCDM J14038-6022
Database references
SIMBADdata
Beta Centauri (β Cen / β Centauri), also known as Hadar or Agena, is the second brightest star in the constellation Centaurus and the tenth brightest star in the nighttime sky. Beta Centauri is a blue-white giant star that is approximately 525 light-years from the solar system. The name Hadar comes from the Arabic word for "ground", while the name Agena comes from Latin words for "the knee".

In 1935, J.G. Voute identified Beta Centauri as a double star, giving it the identifier VOU 31. The companion is separated from the primary by 1.3", and has remained so since the discovery, although the position angle has changed slightly. This would indicate that the orbital period is very long, if the pair are actually gravitationally associated. The primary is also a spectroscopic binary, having at least one companion with an orbital period of 352 days, and possibly other companions.

Beta Centauri is well-known in the Southern Hemisphere as the inner of the two "Pointers" to the Southern Cross. A line made from the other pointer, Alpha Centauri, through Beta Centauri leads to within a few degrees of Gacrux, the star at the top of the cross. Using Gacrux, a navigator can draw a line with Acrux to effectively determine south.

The star is not actually shown on the Australian flag, although the Commonwealth Star is placed in a manner suggesting that it is.
This article or section may be confusing or unclear for some readers.
Please [improve the article] or discuss this issue on the talk page. This article has been tagged since August 2007.
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constellation of Orion is the area outlined in the dashed yellow line. Orion contains a striking and well-known star pattern that has the form of a hunter.]] A constellation is any one of the 88 areas into which the sky — or the celestial sphere — is divided.
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Centaurus

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List of stars in Centaurus
Abbreviation: Cen
Genitive: Centauri
Symbology: the Centaur
Right ascension: 13 h
Declination: −50
Area: 1060 sq. deg.
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Right ascension (abbrev. RA; symbol α) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.
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In astronomy, declination (abbrev. dec or δ) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle.
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The apparent magnitude (m) of a celestial body is a measure of its brightness as seen by an observer on Earth, normalized to the value it would have in the absence of the atmosphere.
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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.
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color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. To measure the index, one observes the magnitude of an object successively through two different filters, such as U and B, or B and V, where U is
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color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. To measure the index, one observes the magnitude of an object successively through two different filters, such as U and B, or B and V, where U is
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Variable Star

Author Robert A. Heinlein & Spider Robinson
Cover artist Stephan Martiniere
Country United States
Language English
Genre(s) Science fiction
Publisher Tor Books
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Beta Cephei variables are variable stars which exhibit variations in their brightness due to pulsations of the stars' surfaces. The point of maximum brightness roughly corresponds to the maximum contraction of the star. Typically, Beta Cephei variables change in brightness by 0.
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Astrometry is the branch of astronomy that relates to precise measurements and explanations of the positions and movements of stars and other celestial bodies. Although once thought of as an esoteric field with little useful application for the future, the information obtained by
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Radial velocity is the velocity of an object in the direction of the line of sight (i.e. its speed straight towards you, or away from you). The light of an object with a substantial radial velocity will be subject to Doppler effect, so the wavelength of the light decreases for
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Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector quantity which specifies both magnitude and a specific direction), defined by distance in metres divided by time in seconds.
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The proper motion of a star is the measurement of its change in position in the sky over time after improper motions are accounted for. This contrasts with radial velocity which is the measurement of the change in distance toward or away from the viewer over time.
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A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60) of one degree. [1] Since one degree is defined as one three hundred sixtieth (1/360) of a circle, 1 MOA is 1/21600 of the amount of arc in a closed circle, or
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A year (from Old English gēr) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit.
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A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60) of one degree. [1] Since one degree is defined as one three hundred sixtieth (1/360) of a circle, 1 MOA is 1/21600 of the amount of arc in a closed circle, or
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A year (from Old English gēr) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit.
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Parallax, or more accurately motion parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, caused by the motion of an
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A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60) of one degree. [1] Since one degree is defined as one three hundred sixtieth (1/360) of a circle, 1 MOA is 1/21600 of the amount of arc in a closed circle, or
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Distance is a numerical description of how far apart objects are at any given moment in time. In physics or everyday discussion, distance may refer to a physical length, a period of time, or an estimation based on other criteria (e.g. "two counties over").
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1 light-year =
SI units
01015 m 01012 km
Astronomical units
0103 AU 0 pc
US customary / Imperial units
01015 ft 01012 mi
A light-year or lightyear (symbol:
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parsec (symbol pc) is a unit of length used in astronomy. The length of the parsec is based on the method of trigonometric parallax, one of the oldest methods for measuring the distances to stars.
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In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. It allows the overall brightnesses of objects to be compared without regard to distance.
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Mass is a fundamental concept in physics, roughly corresponding to the intuitive idea of "how much matter there is in an object". Mass is a central concept of classical mechanics and related subjects, and there are several definitions of mass within the framework of relativistic
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The solar mass is a standard way to express mass in astronomy, used to describe the masses of other stars and galaxies. It is equal to the mass of the Sun, about two nonillion kilograms or about 332,950 times the mass of the Earth.
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Luminosity has different meanings in several different fields of science.

In photometry and color imaging

Main article: luminance
In photometry, luminosity
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The solar luminosity, , is a unit of luminosity (power emitted in the form of photons) conventionally used by astronomers to give the luminosities of stars.

It is equal to the luminosity of the Sun, which is 3.827 × 1026 W, or 3.
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A star catalogue, or star catalog, is an astronomical catalog that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this
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