The Talosian system was an inhabited planetary system in the Talos star group. It was a binary system with eleven planets. One of the planets, Talos IV, was inhabited by the Talosians, a technologically advanced telepathic species. (TOS: "The Cage")
Long range scans made by the United Federation of Planets of the system in the 23rd century showed that it was similar to the Sol system. Prior to 2236, this system had not been explored. In that year, the survey ship SS Columbia, while surveying the system, crash-landed on Talos IV. There was only one survivor from the crash, Vina.
In 2254, eighteen years later, the USS Enterprise discovered the fate of the Columbia after being lured to the system by a faked distress call. After escaping the Talosians, the crew recommended that the planet be placed under quarantine, a recommendation that Starfleet Command endorsed. General Order 7 was created to prohibit contact between the Talosians and Federation starships.
In 2267, thirteen years later, the Enterprise returned to the system to deliver a physically disabled Captain Christopher Pike to the care of the Talosians. (TOS: "The Cage", "The Menagerie, Part I", "The Menagerie, Part II")
In 2293, the location of Talos in the Milky Way Galaxy was labeled in a star chart that was in Captain James T. Kirk's quarters aboard the USS Enterprise-A. (Star Trek VI: The Undiscovered Country okudagram)
- Talos A (star)
- Talos B (star)
The Talosian system was at one point to have been a double star system. (The Making of Star Trek, pp. 93 and 96) Before production on that episode, Gene Roddenberry conceded that he was somewhat "at a loss [...] on exactly what it should look like," and further commented, "If it is too bizarre or confusing to the audience, we'll probably have to go back to a single sun." (The Making of Star Trek, p. 96) The map for the system showed two stars of equal size at the center of the star system; however, when the shore leave party was on the surface, it's not possible to see the suns as the sky was overcast.
According to Star Trek: Star Charts (p. 37) and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), the Talos system was a binary system with two M-class stars. It was located in the Alpha Quadrant.