The Copernicus Star System was a star system consisting of ten planets that before Stardate 4575.9 was destroyed by an alien fleet of autonomous units when they aged its primary star into entering the supernova phase of its life in order to harvest stellar matter to refuel and replicate themselves.
Copernicus VII was an inhabited planet affiliated with the Federation or perhaps a Federation colony. Its inhabitants sent out a distress signal prior to the star's destruction, bringing in the USS Enterprise to investigate. Sadly the starship arrived to late to render assistance to the inhabitants.
The inner planets had all been destroyed by the generated supernova and the orbits of the three surviving outer planets had been severely disrupted.(TOS comic: "Swarm (comic)")