The Pallas 14 system was a star system which contained at least three planets, and was located near the edge of the Milky Way Galaxy. By the late 23rd century, the system was the Federation's most remotely inhabited system.
In 2269, the system was invaded by a huge cosmic cloud creature, which began to consume matter contained within the system, beginning with the planet Alondra. Thankfully, the crew of the USS Enterprise were able to communicate with the creature and persuade it to stop its approach to the inhabited planet, Mantilles. (TAS episode: "One of Our Planets is Missing").
By the year 2289, Leonard McCoy's daughter Joanna McCoy would be living in the city of Ravent, on the planet Mantilles, herself likewise working at a city hospital as a doctor. (TOS - Crucible novel: Provenance of Shadows)