History and specifics
In 2265, Starfleet discovered a comet heading towards Trill just outside the Trill system. The Starfleet team noted that the comet did not match the cometary halo that surrounded the star system. (DS9 - The Lives of Dax short story: "Sins of the Mother")
In the 31st century, Benjamin Sisko sent a starship carrying the Dax symbiont from the Bajoran wormhole to the Trill system to save the symbiont after its host died in the Gamma Quadrant. (ST short story: "The Law of Averages")
- In TNG video game: Birth of the Federation, the orbital configuration of the game map star systems, including this system, was randomly generated each time a new game started. Star Trek Timelines establishes the planet as "Trill" and it's star as "Trillius Prime".