Alpha-Centauri

Alpha-Centauri is a triple-star planetary system and is the Capital System of the Galactic Union. The star system consists of three stars: Alpha Centauri A and Alpha Centauri B, which form the binary star Alpha Centauri AB, and Proxima Centauri. The system has three planets in its orbit: Alpha a, Proxima b, and Proxima c. The former orbits Alpha Centauri AB, while the latter orbits Proxima Centauri.

Alpha a
Alpha a is mostly known as the location of the Centauri Citadel, the military facility where the top officials of the Galactic Union's military reside. The Citadel serves as the Union's main war room, where the Union's military officials organize and plan new military campaigns and strategies.

Proxima b
Proxima b is generally considered uninhabitable due to extreme stellar winds, and efforts to terraform the planet were abandoned. Instead, a number of Orbitals were stationed at that planet. While officially purposed to be a military supply facility, named Spacefleet Logistics Post 413, its true purpose, concealed from most of even the highest echelons of the Union government, is as a research facility for the design and production of weapons of mass destruction, such as the ZG-1.

Proxima c
The planet Proxima c is the most populated planet in the Galactic Union, with a population of roughly 1.1 billion from the 2250 census. It holds the capital city of the Galactic Union, and is a seat of power of the Union's government, being the site of major government referendums.