Solarion was a star with an associated system in Federation space, proximate to the border of the Cardassian Union and the Demilitarized Zone. With at least four planets, it was the nearest Federation system to the Salva system. Solarion IV was one of the planets in this system, and previously held a Federation colony until it was attacked and destroyed by the Cardassians. (TNG - Slings and Arrows eBook: A Weary Life)
During the Borg Invasion of 2381, Federation President Nanietta Bacco called a summit of ambassadors from local star powers, hoping to gather a fleet to stop the Borg Collective's forces. She met privately with Elim Garak, who expressed concerns that the Cardassian fleet would be inadequate, claiming that a fleet under Gul Erem was undergoing training exercises, and the Cardassian Union was in need of basic necessities like land and food. In order to convince Garak to support their cause, she offered three star systems - Argaya, Lyshan, and Solarion. (ST - Destiny novel: Mere Mortals) As of May of that year, the assimilation of these systems into the Union was behind schedule. (ST novel: A Singular Destiny)
- The system's name was spelled "Sol Arion" in A Weary Life, but as "Solarion" in all other sources.