Alpha Centauri ABC

(Aka Rigil Kentarus) The brightest star in the southern constellation of Centaurus and the third brightest star in the night sky, the Alpha Centauri system is located 4.37 ly from Sol, making it the closest star system to the Solar System. Alpha Centauri AB are about 5.6 to 5.9 billion years of age. Despite the advanced ages of the stars, life seems to have developed more recently and is not as advanced. Due to the large distance between Alpha Centauri A, B and C there are no gas giants in this star system. The remains of a gas giant, which became a hot Jupiter, is in close orbit of Alpha Centauri C (Proxima Centauri). Alpha Centauri B orbits around Centauri A in an eccentric elliptical orbit. Alpha Centauri A, B and Proxima are visible at times from the planets at differing points in their orbits. Proxima Centauri orbits Centauri AB at a distance of 13,000 AU or 400 times the orbital distance between Neptune and Sol.

Alpha Centauri A is the principal member, or primary, of the binary system, is slightly larger and more luminous than the Sun. It is a solar-like main-sequence star with a similar yellowish color whose stellar classification is spectral type G2 V.  From the determined mutual orbital parameters, Alpha Centauri A is about 10% more massive than the Sun, with a radius about 23% larger.

Alpha Centauri B is the companion star, or secondary, of the binary system, and is slightly smaller and less luminous than the Sun. It is a main-sequence star is of spectral type K1 V, making it more an orange color than the primary star.  Alpha Centauri B is about 90% the mass of the Sun and 14% smaller in radius. Although it has a lower luminosity than component A, star B emits more energy in the X-ray band and there has been at least one observed flare. Alpha Centauri A would appear as bright as the full Moon from a planet orbiting Alpha Centauri B.

Alpha Centauri C, also known as Proxima Centauri, is of spectral class M5 Ve or M5 VIe, suggesting this is either a small main-sequence star (Type V) or subdwarf (VI) with emission lines.

Alpha Centauri is a “blaze system” and can be reached by blazing 4.3 ly from the Sol system.

## **Planets**

#### **Centauri A**

**Centauri Ab:** A small rocky planet .75 AU from the star. It is .59 the size of Earth and its orbit is too close to the star to sustain life.

#### **Centauri B:**

**Centauri Bb:** Slightly smaller than Earth it orbits the star at 0,98 AU from the star and is shrouded in superheated gasses much like Venus in Sol’s orbit.

**Centauri Bc:** This planet, known to Earth Republic cartographers as Chiron I, is 1.3 AU from the star and is 2.3 times larger than Earth. With a slower rotation and weaker magnetic field than that of Earth the atmosphere and gravity have been measured within the range of compatibility with Earth based life forms. Centauri Bc is a warm-temperate world with liquid water and primitive life forms inhabiting the oceans and coastal areas. Plant life is extensive near bodies of water, but also in primitive forms with few flowering or fruit bearing plants. The planet has a single continent which shows signs it is in the beginning stages of breaking apart via continental drift. The most suitable interior locations for a colony are in proximity to volcanic activity.

**Centauri Bd:** This planet is 3.4 AU from the star and outside the habitable zone. However due to the composition of its atmosphere makes it warmer than expected, though it is still a frozen world. Low temperatures are a chilly -75 ranging to a high of 0 degrees. This planet would be habitable for Earth based life forms, but would require bio-domes or extensive terraforming to be ideal for colonization. There are no known life forms on Centauri Bd.

**Centauri Be:** A large rocky planet 5.6 AU from the star, it is outside the habitable zone and is 7.4 Jupiters in size. This world is uninhabitable due to the lack of sufficient atmosphere, crushing gravity and extremely low surface temperatures. The thin atmosphere is subject to nearly constant disturbances of static electrical discharge which is generated by methane snow blowing over the frozen planetary surface.

#### **Centarus C (Proxima):**

**Centarus Cb:** A large rocky planet .25 AU from the star Centarus Proxima. This world is the remnant of a hot Jupiter which burned up millions of years ago. The charred surface is scarred by fissures and is cold and lifeless.