Thelonii is a star system located a number of parsecs away from Earth and the Sol system, in Federation space, in quadrant 0 near the border between the galaxy's Alpha and Beta Quadrants. Thelonii was a trinary star, consisting of the three stellar bodies Thelonii, Xanthii and Alfr.
History and specifics[]
The Federation starship USS Thelonii was named for this location. (ST reference: Star Fleet Technical Manual)