Alpha Centauri facts for kids
The Apparent Orbit (thin ellipse) is the shape of the orbit as seen by the observer on Earth. The True Orbit is the shape of the orbit viewed perpendicular to the plane of the orbital motion. According to the radial velocity vs. time, the orbit is divided here into 80 points, and each step refers to a timestep of almost a year.
Alpha Centauri is the brightest star in the southern Centaurus constellation. It is the fourth brightest star in the night sky, with a magnitude of -0.01. It is visible in the Southern Hemisphere, and is too far south for most of the Northern Hemisphere to see.
Alpha Centauri is a binary star system of two stars A & B. The distance between them is quite close. To the naked eye, the stars are too close for the eye to be able to see them as separate. Their orbit is about the distance of the giant planets from our Sun.
There is a third star, Proxima Centauri (or Alpha Centauri C). This is usually considered separately, but in fact it is also gravitationally connected to the other two. It is actually slightly closer to us, with a very much larger orbit around A and B.
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System
Viewed as a triple star system, Alpha Centauri is the closest to our own, being 4.2-4.4 light years (ly) away. It consists of two main stars, Alpha Centauri A and Alpha Centauri B (which form a binary star together) at a distance of 4.36 ly, and a dimmer red dwarf named Proxima Centauri at a distance of 4.22 ly. Both of the two main stars are rather similar to the Sun. The larger star, Alpha Centauri A, is the most similar to the Sun, but a little larger and brighter.
- The next closest star is Barnard's Star.
Related pages
Images for kids
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The Very Large Telescope open to the night sky, with the Milky Way running diagonally across the sky above it and many southern stars and constellations labelled and connected by lines, including Alpha Centauri and the not visible Proxima Centauri.
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Alpha Centauri (Rigel Kentaurus) around the South celestial pole
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Alpha Centauri (with unlabeled Proxima Centauri) on a radar map of all known stellar and substellar objects within 9 light years (ly), arranged clockwise in hours of right ascension, and marked by distance (▬) and position (◆). Distances are marked outward from the Sun (Sol), with concentric circles indicating the distance in one ly steps. Positions are marked inward from their distance markings, connected by lines according to their declinations (doted when positive), representing the arcs of the declinations viewed edge-on.
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Distances of the nearest stars from 20,000 years ago until 80,000 years in the future
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Apparent and true orbits of Alpha Centauri. The A component is held stationary, and the relative orbital motion of the B component is shown. The apparent orbit (thin ellipse) is the shape of the orbit as seen by an observer on Earth. The true orbit is the shape of the orbit viewed perpendicular to the plane of the orbital motion. According to the radial velocity versus time, the radial separation of A and B along the line of sight had reached a maximum in 2007, with B being further from Earth than A. The orbit is divided here into 80 points: each step refers to a timestep of approx. 0.99888 years or 364.84 days.
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ESO - Alpha Centauri in the HR-System (by)
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The discovery image of Alpha Centauri's candidate Neptunian planet, marked here as "C1"
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Looking towards the sky around Orion from Alpha Centauri with Sirius near Betelgeuse, Procyon in Gemini, and the Sun in Cassiopeia generated by Celestia
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Diagram of the closest stars to the Sun, within 7.5 light years
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See also
In Spanish: Alfa Centauri para niños
