Alpha Centauri in Fiction - The Alpha Centauri System

The Alpha Centauri System

Alpha Centauri, a double star system with the binary designation Alpha Centauri AB, is the brightest visible object in the southern constellation Centaurus. Its component stars are Alpha Centauri A (the primary—somewhat larger and brighter than the Sun) and Alpha Centauri B (the secondary—slightly smaller and dimmer). These stars are of spectral classes G2V (as is the Sun) and K1V respectively; in the former case there is an obvious model and potential for planets capable of supporting complex biospheres, and in the latter, as it turns out, an even stronger probability of a stable habitable zone that is well suited for life. Alpha Centauri C (Proxima Centauri—a late-discovered red dwarf, and the closest known star to the Solar System) appears to be gravitationally bound to the AB system although at a considerable distance. The collection of three stars together is called Alpha Centauri AB-C.

Since both of the principal stars A and B are nearby and similar to the Sun, astronomers have pursued a detailed search for planets in the Alpha Centauri system. The discovery of the Earth-sized planet Alpha Centauri Bb (see graphic) was announced on October 16, 2012, although this planet orbits far too close to its sun (at about 0.04 AU) to support life. Several established planet-hunting teams have used various radial velocity and star transit methods in this quest, but their observations have so far (as of 2012) failed to find any evidence of such relatively easy-to-detect orbiting objects as brown dwarfs or gas giant planets.

Alpha Centauri AB appears to the unaided eye as a single star with a combined apparent magnitude of –0.27, making it the third brightest in the night sky after Sirius and Canopus. However, it lies so deep in the southern sky that most Euro-American creators of science fiction have never seen it with their own eyes; their strong interest in the system, expressed in stories involving the early stages of interstellar travel, is based wholly on its astrometrically established proximity to the Earth. In these stories Alpha Centauri is often treated as if it were a single star. The dim tertiary companion Proxima Centauri is frequently overlooked as being our true closest stellar neighbor in favor of Alpha Centauri AB (see further Proxima Centauri in fiction).

Alpha Centauri is commonly referred to as Rigil Kentaurus (Arabic: رجل أقنطورس Rijl Qantūris), meaning foot of the centaur—compare Rigel in Orion—and also as Toliman (Arabic: الظلمان al-Zulmān), or the ostriches.