Ikeya is covered in depth on the Twilight site.
Namely it is used for GTVI deep range research, and there is a single habitable world which is colonized from the rubble of the great war.
Ribos during the great war housed the GTA's primary spaceyards. After the Battle of Capella, it's become of importance once again.
Antares is one of the GTVA's core systems though it is heavilly contested between Terran and Vasudan populations.
It includes several GTVI-held spaceyards in orbit of it's arid outer-most world, Segunchi.
Altair is primarily research outposts studying the Vallettan-age ancients. (note: these are the creators of the Knossos device and sub-space tracking, though allied scientists have determined that the technology is based off of an earlier culture)
Vasuda Prime is home to some of the largest spaceyards in allied space, the world itself is now barren and devoid of almost all life, however many of the great Vasudan cities have been rehabited and terraforming projects have been extremely sucessful in brining the world back to life.
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AceStaff member FreeSpace Watch
http://freespace.volitionwatch.com/