Alpha Centauri


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Related to Alpha Centauri: Proxima Centauri, Andromeda galaxy

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 ?
Using the European Space Organization's HARPS instrument, astronomers already discovered a planet orbiting Alpha Centauri B.
It's so close that from some southern places on Earth, you can see Alpha Centauri B in the night sky without a telescope.
Polyphemis: An enormous planet, a gas giant almost twice the size of Jupiter, which in turn orbits the yellow sun of Alpha Centauri B.
Alpha Centauri is the 4th brightest star in the night sky.
27 Alpha Centauri is actually a Centauri star system made up of three system stars that are bound together by their gravitational pulls.
The next closest is Proxima Centauri, which is the dimmest star in the Alpha Centauri star system which consists of three stars.
I think we should take all the world's leading politicians, put them in a large spacecraft, and send them on a one- way journey to Alpha Centauri - Astronomer Sir Patrick Moore, 81
Set in 2079, with the Earth locked in a brutal war with Alpha Centauri, the story tells of government agents who believe that one of their top scientists, Spencer Olham (Gary Sinise), has been replaced by a replicant who is a walking bomb that can't be detected.
They might arrive on Alpha Centauri to find a thriving colony draping a red carpet out for them.
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At this time, the British astronomer Thomas Henderson (1798-1844) measured the parallax of Alpha Centauri from his observatory at Capetown in South Africa.
Anderson's real story is about the few obsessive folks who cross the gulf of stars to found a new society on a planet orbiting Alpha Centauri.