Alpha Centauri

Alpha Centauri is a triple-star system about 4.37 light-years from Earth, comprising the Sun-like stars Alpha Centauri A and B and the red dwarf Proxima Centauri.

Alpha Centauri A: A G-type main-sequence star and the more luminous primary of the Alpha Centauri A–B pair. It is one of the system’s two close, gravitationally bound Sun-like stars.
Alpha Centauri AB: The close binary formed by Alpha Centauri A and Alpha Centauri B. Its roughly 80-year orbit is the system’s inner gravitational structure.
Proxima Centauri b: An exoplanet orbiting Proxima Centauri, discovered through measurements of its host star’s motion. It is the best-known planet associated with the system.
Thomas Henderson: A Scottish astronomer who measured the parallax of Alpha Centauri in the 1830s. His observations helped establish the system’s distance from Earth.
Sirius: The brightest star in Earth’s night sky, a binary system about 8.6 light-years away. It is brighter in the sky but farther from Earth than Alpha Centauri.
Alpha Centauri B: A K-type main-sequence star that orbits Alpha Centauri A in a close binary pair. Its orbit around A defines the system’s central stellar pair.
Proxima Centauri orbital motion: The long-period motion of Proxima Centauri around the Alpha Centauri AB pair. It describes how the distant red dwarf remains bound to the inner binary.
Radial velocity method: A planet-detection technique that measures periodic shifts in a star’s spectral lines caused by orbital motion. It revealed the gravitational signal used to discover Proxima Centauri b.
Friedrich Wilhelm Bessel: A German astronomer who made the first successful stellar parallax measurement, for 61 Cygni. His work established the method used to measure nearby stars such as Alpha Centauri.
Barnard's Star: A solitary red dwarf about six light-years from Earth, noted for its large proper motion. It is a nearby single star, unlike Alpha Centauri’s gravitationally bound trio.

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