Sontar system

The Sontar system (COMIC: Supremacy of the Cybermen) was the star system containing the planet Sontar, homeworld of the Sontarans, and its moon. (AUDIO: The First Sontarans)

The system contained a G0 star and existed in either the southern spiral arm of the Mutter's Spiral (PROSE: Lords of the Storm) or the Metasaran Galaxy. (TV: The Last Sontaran) Sontar originally orbited its star like any other planet, but by 1609 it had been modified so that the star orbited Sontar as a more "logical" pattern. (PROSE: The Empire of Glass)

In an alternate timeline, the Cybermen had invaded the system to attack at Sontar directly. (COMIC: Supremacy of the Cybermen)