Tarchannen system

The Tarchannen system was an uninhabited planetary system. This system consisted of a primary and at least three planets. The third planet was the homeworld for the non-sentient Tarchanne. (TNG: "Identity Crisis")

In the script, the pronunciation for Tarchannen was "tar-CHAN-in". [1]
The script thrice described Tarchannen III as being a world of "perpetual twilight"; it was unclear whether this referred to the brightness of the system's sun or the planet itself being tidally-locked.