Alpha Centauri
Overview
Alpha Centauri is the closest star system and closest planetary system to Earth's Solar System at 4.37 light-years (1.34 parsecs) from the Sun. It is a triple star system, consisting of three stars: α Centauri A (officially Rigil Kentaurus), α Centauri B (officially Toliman), and α Centauri C (officially Proxima Centauri).
System
The Alpha Centauri system is located 1.34 parsecs or 4.37 light years from the Sun, making it the closest star system to the Solar System. Although it appears to the unaided eye as a single object, Alpha Centauri is actually a binary star system (Alpha Centauri A and B) whose combined light contributes to its overall apparent magnitude of -0.27, making it the third-brightest star seen from Earth after the -1.46 magnitude Sirius and the -0.72 magnitude Canopus.
Stars
Alpha Centauri A
Alpha Centauri A, also known as Rigil Kentaurus, is the principal member, or primary, of the binary system. It is a solar-like main-sequence star with a similar yellowish color, whose stellar classification is spectral type G2 V.
Alpha Centauri B
Alpha Centauri B, or Toliman, is the secondary member of the binary system. It is an orange-hued main-sequence star of spectral type K1 V.
Alpha Centauri C
Alpha Centauri C, better known as Proxima Centauri, is a small, low-mass star located 4.24 light-years away from the Sun. Despite its proximity, Proxima Centauri cannot be seen with the naked eye due to its apparent magnitude of 11.05. It is a red dwarf of spectral type M5.5 and is the least massive of the three stars in the Alpha Centauri system.
Planetary system
The Alpha Centauri system is also the closest known planetary system to our Solar System. As of 2021, there are confirmed planets orbiting two of the three stars in the system.
Proxima Centauri b
Proxima Centauri b is an exoplanet orbiting in the habitable zone of Proxima Centauri. It was discovered in 2016 and has a minimum mass of 1.27 Earth masses.
Alpha Centauri Bb
Alpha Centauri Bb is a planet that was reported to be orbiting Alpha Centauri B, discovered in 2012. However, its existence was later put into doubt and as of 2021, it is considered a disproven planet.
Observation and exploration
Due to its proximity to Earth, Alpha Centauri has been proposed as a viable destination for interstellar travel. Projects such as Breakthrough Starshot aim to send a fleet of miniaturized spacecraft to the Alpha Centauri system.