Gustav

One of the very first human colony worlds. Formerly known as Alpha Centauri, Gustav is very close to Sol. The colony was destroyed in the first AI war (2900) by a rogue Artificial Intelligence AI - and the system has remained off-limits ever since (to the extent that it is not shown on star maps any more). A small orbital monitoring force remains in the system, manned by Centauri Conglomerate personnel.
The destruction of the colony is remembered every year in Centauri space on Gustav Day (traditinally Day 256 of the StarYear) where robots are ritually burnt in effigy.