The Altair system was an inhabited planetary system in Sector 9. The system, which consisted of at least six planets, was of strategic importance to the Federation in the mid-23rd century. (TOS: "Amok Time", "Wolf in the Fold"; TNG: "Encounter at Farpoint") Planets of the Altair system were the origin of such consumables as Altair water, the champagne Altairian Grand Premier, and the Altair sandwich. The Altarian encephalitis, a disease, originated in this system. (Star Trek III: The Search for Spock; TNG: "Datalore", "Future Imperfect"; DS9: "You Are Cordially Invited"). In the 2280s, a freighter could travel in nineteen periods from Altair to reach Gamma Hydra sector, Section 10. (Star Trek II: The Wrath of Khan)
The Altair system had been involved in a long interplanetary conflict. The inauguration of the new president on Altair VI in 2267 helped to stabilize the area. The Federation sent three starships, including the USS Enterprise, to this historic event as a demonstration of friendship and strength. This demonstration was intended to cause ripples all the way to the Klingon Empire. (TOS: "Amok Time")
Background information Edit
According to Star Trek: Star Charts (p. 44, "United Federation of Planets I") and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), the Altair (Alpha Aquilae) system was located in the Alpha Quadrant. The primary was an A-class star. In the 22nd century, this system was a destination on Earth and Vulcan trade routes. In the late 24th century, the system was largely independent, with only Altair IV listed as a Federation member.