Alpha Centauri System

61 Alpha Centauri A

System Nature: Trinary

Position: Primary (A)
Name: Alpha Centauri A
Spectral Class: G2 V
Color: Yellow
Type: Main Sequence Star
Coordinates: -1.7X, -1.4Y, -3.9Z
Mass: 1.02.Sol
Absolute Bolometric Magnitude: 4.35
Effective Surface Temperature: 5630°K
Luminosity: 1.65 Sol
Radius: 1.01.Sol
Life Zone: 1.06 au – 1.55 au
Optimum Distance: 1.28 au

Position: Secondary (B)
Name: Alpha Centauri B
Spectral Class: K0 V
Color: Orange
Type: Main Sequence Star
Coordinates: -1.7X, -1.4Y, -3.9Z
Mass: 0.82 Sol
Absolute Bolometric Magnitude: 5.69
Effective Surface Temperature: 4990°K
Luminosity: 0.69 Sol
Radius: 0.90 Sol
Mean Distance to Primary: 23.47 au
Absolute Distance to Primary (A): 11.25 au – 35.44 au
Orbital Ecliptic Eccentricity: 24.19 au
Orbital Period: 79.1 Terran Years
Life Zone: 0.68 – 0.99 au
Optimum Distance: 0.83 au

Position: Secondary (B)
Name: Alpha Centauri B
Spectral Class: K0 V
Color: Orange
Type: Main Sequence Star
Coordinates: -1.7X, -1.4Y, -3.9Z 61 Alpha Centauri B
Mass: 0.82 Sol
Absolute Bolometric Magnitude: 5.69
Effective Surface Temperature: 4990°K
Luminosity: 0.69 Sol
Radius: 0.90 Sol
Mean Distance to Primary: 23.47 au
Absolute Distance to Primary (A): 11.25 au – 35.44 au
Orbital Ecliptic Eccentricity: 24.19 au
Orbital Period: 79.1 Terran Years
Life Zone: 0.68 – 0.99 au
Optimum Distance: 0.83 au

Binary Life Zone (A+B): 1.26 au – 1.84 au Binary Optimum Distance (A+B): 1.53 au

Position: Tertiary ©
Name: Proxima Centauri
Spectral Class: M5 V
Color: Red
Type: Main Sequence Star
Coordinates: -1.6X, -1.2Y, -3.8Z
Mass: 0.32 Sol
Absolute Bolometric Magnitude: 15.45
Effective Surface Temperature: 2810°K
Luminosity: 0. 00081 Sol
Radius: 0.34 Sol
Mean Distance to Primary: 10,114.65 au
Absolute Distance to Primary (A): 10,099.64 – 10,122.07 au
Orbital Ecliptic Eccentricity: 22.43 au
Orbital Period: 2,488,156.5 Terran Years

The Alpha Centauri system has three stars: Alpha Centauri A, Alpha Centauri B (which orbits Alpha Centauri A with a period of about 79 years), and Proxima Centauri (which orbits the Alpha Centauri A/B binary system at about 10,000 AU). This complicated series of stars has an equally complicated family of planets.

61 Alpha Centauri A and BThe orbital mechanics of the system have swept large regions of it clear of planetesimals, and have greatly disturbed the orbits of most of those which remain. All worlds of the A/B system show evidence of heavy meteor strikes (although erosion has largely obliterated traces of these strikes on Tirane and Limbes).

Alpha Centauri A and Planets

The star itself is a G2V with mass, radius, and luminosity almost identical to Sol. Alpha Centauri A has three worlds in orbit about it, one of which is Tirane, the first world reached by humanity in its journey starward. Tirane occupies the first orbit, within the life zone of the star. It has two satellites: the small ice ball Esa and the more distant rocky moonlet Europos. The second orbit holds the tiny desert world Oikemenos, roughly 5,000 kilometers in diameter. The final orbit around Alpha Centauri A is occupied by the 6000-kilometer-diameter failed core world Neuerde.

Alpha Centauri B and Planets

Alpha Centauri B orbits Alpha Centauri A at a distance which varies from 11 to 35 AU. This second star in the system is a KO V star, similar in size and mass to Sol but less than half as luminous. Alpha Centauri B is orbited by six worlds, the innermost being Sheol, a large hothouse world tidally locked to its parent star. The second orbit holds Hades, a smaller rocky world too hot to be useful. Limbes, the planet in the third orbit, was habitable about 800 million years ago, but has since become a victim of a runaway greenhouse effect. The next two worlds are Enfer and Vorholle, both failed core worlds approximately 10,000 kilometers in diameter. The final orbit is occupied by Purgatoire, a frozen ice ball world on the very edge of Alpha Centauri B’s family of planets.

61 Proxima CentauriLimbes is a former garden world sterilized by a runaway greenhouse effect, and it is of interest only to scientists and a few crackpots. A joint ESA research station is maintained in orbit around the world, although its staff has been drastically reduced as the years have passed, and other, more interesting worlds have been discovered. Despite almost a century of study, no surviving life forms have been detected, but fossil evidence indicates a rich biosphere just under a billion years ago. Over 1,800 separate genera have been described, although their exact relationships remain tentative since most of the remains are fragmentary (over 800 million years have passed since the last of them was alive, after all).

A small Terran religious cult holds that Limbes (which they name Ramtha) once had an interstellar civilization which seeded Earth with life. The cult is gathering funds for a massive archeological expedition to the world in order to prove their contentions. Conventional xenological organizations dismiss such claims (1 6 exploratory parties have been sent to Limbes and have failed to discover any evidence that the world ever had intelligent life, let alone an interstellar capability). Ramtha devotees claim that volcanic activity has concealed the evidence of civilization and believe the last survivors of the planetary disaster which overtook Limbes now lie in suspended animation deep beneath the surface of the world, awaiting the proper moment to reveal themselves to their descendants and initiate a golden age of enlightenment and universal peace. Detractors claim that Ramtha devotees have been watching too many low-budget science fiction movies.

Sheol is a hothouse with fairly large mineral deposits, but the atmosphere and climate are particularly harsh, and there are more economically exploitable deposits of the same minerals elsewhere in the system. A combined Mexican/Argentinian research station is maintained in orbit around the world.

The Binary System (Alpha Centauri A & B) and Planets

The two stars together are orbited by nine other worlds, making a total of 18 worlds (plus assorted satellites and other planetoids) in the Alpha Centauri A/B system. The first, Gallia, orbits at 106 AU and is a large gas giant. At 1 15 AU orbits Britannia, a relatively small ice ball world which nonetheless has three satellites: Caledonia, Ordovicia, and Siluria. Further out are Italia, a large failed core world, and Germania, a smaller ice ball. Finally, at 41 1 and 71 0 AU respectively are Hispania and Lusitania, two similar failed core worlds almost too far away from the system’s stars to enjoy any of their radiation.

Proxima Centauri and Planet

Proxima Centauri is a small M5 V star which orbits the A/B system at 10,000 AU. Proxima is orbited by a single gas giant, Moiroi, and its associated satellites, Clotho, Lachesis, and Atropos.

The system is uninhabited except for a few scientific installations (engaged in the study of the first flare star humanity could observe at close range), and a Korean mining operation on Lachesis. The largest remaining installation is the former French observatory on Clotho, which was sold to Brazil in 2254 and now houses one-fifth of its original complement of 1800. Australia and Indonesia maintain small scientific stations on Clotho and Atropos respectively (the former American station on Atropos was given to the Indonesians in 2242).

Alpha Centauri System

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