Alpha Centauri

Alpha Centauri (Rigil Kentaurus) is the nearest star system to the Earth beyond the Sun. The entire system has three stars: the two larger stars form a binary star: Alpha Centauri A, a G2V-type star with absolute magnitude +4.38 and Alpha Centauri B a K1V-type star with absolute magnitude +5.71. They co-orbit in about 80 years, their eccentric orbit varying the distance between them from 11 to 37 AU. Without a telescope, the two have the appearance of a single star,

The third star is Alpha Centauri C or Proxima Centauri, a red dwarf of spectral type M5.5Ve and an absolute magnitude of +15.6. It is currently the closest of the three to Earth, orbiting the binary system about once every half million years, currently about a fifth of a light-year (ly) and about 2 degrees' angular distance from the pair, but cannot be seen without a telescope. It has a confirmed extra-solar planet of interest, Proxima b, that appears to be in its habitable zone.

Characteristics (Alpha Centauri A):

• Centaurus - constellation.
• 14h39m36.49400s - right ascension.
• -60deg50m02.3737s - declination.
• +0.01 - apparent magnitude (V).
• 4.34 ly - distance (1.33 pc or roughly 27500 AU).
• G2V - spectral type.
• 1.1 - mass(solar).
• 1.5 - luminosity(solar).
• 1.2175 - radius(solar).
• +0.71 - B-V color index.