(covers information from several alternate timelines)
Eminiar was a primary in the Eminiar system. This system was located within the stellar cluster NGC 321. Two planets in this system, Vendikar (Eminiar III) and Eminiar VII, were inhabited by a humanoid species.
In 2293, the location of Eminiar 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)
In 2366, in an alternate timeline, during the Federation-Klingon War, the location of Eminiar was labeled on a tactical situation monitor in the ready room aboard the USS Enterprise-D (TNG: "Yesterday's Enterprise", okudagram)