Alpha Centauri

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Related to Alpha Centauri A: Beta Centauri, Proxima Centauri, Alpha Centauri B

Alpha Centauri

(ăl`fə sĕntôr`ē), brightest star in the constellation CentaurusCentaurus
, southern constellation located N and E of Crux, the Southern Cross. It is known especially for its bright stars Alpha Centauri and Hadar. It also contains Centaurus A, a radio galaxy, as well as a globular star cluster visible to the naked eye.
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 and 3d-brightest star in the sky; also known as Rigil Kent or Rigil Kentaurus; 1992 position R.A. 14h39.1m, Dec. −60°49'. Its apparent magnitudemagnitude,
in astronomy, measure of the brightness of a star or other celestial object. The stars cataloged by Ptolemy (2d cent. A.D.), all visible with the unaided eye, were ranked on a brightness scale such that the brightest stars were of 1st magnitude and the dimmest stars
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 is −0.26. Alpha Centauri is actually a triple-star system, the components being designated A, B, and C. Alpha Centauri A is the brightest component; it is a yellow main-sequence star of the same spectral classspectral class,
in astronomy, a classification of the stars by their spectrum and luminosity. In 1885, E. C. Pickering began the first extensive attempt to classify the stars spectroscopically.
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 (G2 V) as the sun and of about the same size and mass. It forms a binary system with the somewhat smaller, less bright, and more orange Alpha Centauri B. Alpha Centauri C, a red dwarf, is also called Proxima Centauri because it is the closest star to the earth (other than the sun), at a distance of 4.28 light-years; components A and B are currently 4.34 light-years away. Proxima Centauri orbits about the common center of mass of the system with a period of more than 250,000 years, so that in about 125,000 years it will be more distant than A and B. In 2012 the discovery of a roughly earth-sized planet orbiting Alpha Centauri B was announced; the planet was reported to orbit the star closer than Mercury orbits the sun. A roughly earth-sized planet has also been identified (2016) orbiting Proxima Centauri, and though it orbits its star much more closely than the Mercury does the sun, it is believed to be in the habitable zone because of the cooler temperatures of Proxima Centauri.

Alpha Centauri

(sen-tor -ÿ, -ee) (Rigil Kentaurus; α Cen) A binary star that is the brightest star in the constellation Centaurus, one of the brightest in the sky, and the second nearest star to the Sun. The two components, A and B, form a yellow-orange visual binary (separation 17″.7, period 80.1 years) and are similar in mass and size to the Sun. Proxima Centauri appears to be physically associated with α Cen; it is the nearest star to the Sun. mv : –0.01 (A), 1.33 (B), –0.27 (AB); Mv : 4.4 (A), 5.7 (B), 4.1 (AB); spectral type: G2 V (A), K1 V (B); mass: 1.09 (A), 0.89 (B) times solar mass; distance: 1.33 pc.

Alpha Centauri

[¦al·fə sen′tȯ·rē]
(astronomy)
A double star, the brightest in the constellation Centaurus; apart from the sun, it is the nearest bright star to earth, about 4.3 light-years away; spectral classification G2. Also known as Rigil Kent.

Alpha Centauri

brightest star in Centaurus constellation; closest star to Earth. [Astronomy: NCE, 74]
References in periodicals archive ?
Compared to the sun, Alpha Centauri A is of the same stellar type, G2, and slightly bigger, while Alpha Centauri B, a K1-type star, is slightly smaller.
Now, by observing Alpha Centauri A in far-infrared light with Herschel and comparing the results with computer models of stellar atmospheres, scientists have made the first discovery of an equivalent cool layer in the atmosphere of another star.
The study of these structures has been limited to the Sun until now, but we clearly see the signature of a similar temperature inversion layer at Alpha Centauri A," Rene Liseau of the Onsala Space Observatory, Sweden, and lead author of the paper presenting the results said.
The European team spent four years using the European Southern Observatory in Chile to look for planets at Alpha Centauri B and its sister stars Alpha Centauri A and Proxima Centauri.
So finding the planet's signature in the star's wobbles meant the team needed to carefully filter out other sources of stellar variability such as star spots, bulges on the star's surface and gravitational interactions with Alpha Centauri A.
The orbit of the other bright component of the double star, Alpha Centauri A, keeps it hundreds of times further away, but it would still be a very brilliant object in the planet's skies.
If Proxima Centauri is gravitationally bound to Alpha Centauri A and B, then the three objects should be moving through space at roughly the same velocity.
I think if a potentially habitable planet is found orbiting Alpha Centauri A or B you might see a ground-swell of excitement and a look at new kinds of propulsion technologies, leading to a mission to send an unmanned probe there in the period of a lifetime.
We are excited to have been chosen by Alpha Centauri as their preferred vendor on these mission critical datasets.