Alpha Centauri

Libby Dix ///// 21 Dec. 2015

Alpha Centauri is a star system that is made up of three stars: Alpha Centauri A, B, and Proxima. This is the closest star system to our Sun; it is also called Rigil Kentaurus and Toliman (Arabic origin).


  • Type of Star: G; Main Sequence
  • 3.5% of known stars
  • Type of Fusion: Hydrogen to Helium
  • Relative Size (Mass and Radius when the Sun is 1): 1.1 M, 1.227 R
  • Distance from Earth: 4.37 light years
  • Color: Yellow
  • Temperature (Kelvin): 5,790 K
  • Luminosity (when our Sun is 1): 1.519 L
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Alpha Centauri played a role in Greek and Roman mythology. It was believed that a wise centaur was wounded by Heracles (a greek mythological figure), so Zeus put the centaur into the sky to be safe. Alpha Centauri is the hoof of the centaur in the constellation Centaurus.


Did you know that scientists have found a planet about the size of Earth near Alpha Centauri B. They call this planet Alpha Centauri Bb. Scientists, however, do not think it will be life sustaining for a while (if ever) due to its closeness to its sun. It has a REALLY hot surface! Below, you can see an artist's impression of the planet.
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The stages of this star's life are pretty typical compared to an average star. It goes through the same four steps. So far, Alpha Centauri (A) has already been through the first stage (nebula coming together). Right now, it is a Main Sequence Star, where it spends it's time fusing hydrogen into helium. After that, this star will become a Red Giant Star. Alpha Centauri is about the same size and age as our Sun, so it will become a Red Giant Star at about the same time (5 billion-ish years from now).


Alpha Centauri was first discovered in 1592 by Robert Hues. Astronomers learned more about this marvelous star using micrometrical observations (1834), and in the 20th century started using photographic plates, Hipparcos star catalog (a satellite) and Hubble Space Telescope. We are continuing to learn more and more about these 3 stars every day!