The Tuun System is a star system that will be added in KSP2. The name of the system was not officially announced, but discovered in the game's files by u/DartFrogYT on Reddit, along with the Qeg System.
The system moves in a figure-eight style configuration with a radius of 0.2 units. The system is offset by 3.6 X axis and 1.1 Z axis units from Kerbol, making it the second closest of the other star systems, and roughly analogous in position to Barnard's Star.
A list of celestial bodies found in the game code lists these planets and moons in the Tuun system: