S'Arl

From Tardis Wiki, the free Doctor Who reference

S'Arl, the sixth planet orbiting Hadar, was the home planet of the Tzun. After the Tzun attempted to colonise Veltroch in 2172, the Veltrochni retaliated. Within two years, the Veltrochni turned S'Arl into a radioactive cinder, rendering it uninhabitable. (PROSE: First Frontier) Using quantum lances, they were able to cut right through the crust of S'Arl and into the mantle. (PROSE: The Dark Path)

This suggests S'Arl was destroyed after it was made uninhabitable.