These are star systems that were mentioned but not named.
This system accompanied the star Amargosa and included the Amargosa observatory, a space-based Federation facility. In 2371 the facility was attacked by Romulans, sparking concern of a new Romulan threat in the sector. At the time the Enterprise detected no ships in the system, though a cloaked Klingon ship was present. Shortly thereafter, a trilithium weapon launched into Amargosa by the rogue scientist Tolian Soran triggered the star to collapse, producing a level twelve shock wave expected to destroy everything in the system. (Star Trek Generations)
Gamma quadrant binary star systemEdit
This binary system was close to the Gamma Quadrant exit of the Bajoran wormhole in a sector Starfleet was only beginning to explore when they were forced to urgently chart the system after a runabout crash in 2369. The system contained at least seven planets, two dozen or so moons, and an asteroid belt. The sixth planet had three moons. The third planet contained one moon, which was made into a penal colony. For more information on that moon, see Penal moon.
The star emitted an abnormally large amount of delta radiation, making scanning the system difficult. Scans indicated no M class planets, making survival seem impossible, though these scans could not be trusted, and a life-sustaining moon was later found.
New Berlin colony systemEdit
This unnamed system was administered by the Federation New Berlin colony. In 2369, the colony sent out a distress call fearing a Borg incursion, while all that had happened was that a Ferengi trader had entered their system. (TNG: "Descent")
Nygean homeworld's systemEdit
This system, uncharted according to Starfleet, had several planets including one that was Minshara class. The system turned out to be claimed and defended by the Romulan Star Empire, which did not tolerate others entering it. (ENT: "Minefield")
This Delta Quadrant system contained Sikaris, homeworld of the Sikarians. It had a single sun, around which Sikaris revolved at a distance of almost forty thousand light years divided by two and a half billion. (VOY: "Prime Factors")
System with Kuiper beltEdit
Terra Nova systemEdit
This system was home to the xenophobic Tholians. When Enterprise encountered a Tholian vessel in 2152, T'Pol remarked that it was unusual for Tholians to travel that far from their system. (ENT: "Future Tense")
Sigma Iotia Edit
Described by Captain James T. Kirk as being on "...the outer reaches of the galaxy", this unnamed star system had at least two planets. The second planet, Sigma Iotia II, was the homeworld of the Iotians. (TOS: "A Piece of the Action")