Trill system

The Trill system is an Alpha Quadrant star system in which Trillius Prime, the Trill homeworld, is located.

Starbase 51 is the closest Starfleet base to the the Trill system. 

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. (SS DS9 (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. (SS ST (The Law of Averages))