Kallana

A planet under the jurisdiction of Jaffa formerly loyal to Cronus. The planet was chosen by the Ori to be the location of a Supergate that would bring their forces into the Milky Way.

A Prior arrived on Kallana, rid himself of the Jaffa population and initiated an Ori force field which eventually engulfed the entire planet. Once this was done, the force field shrank the mass of Kallana until the world had become a singularity, designed specifically for powering the Supergate indefinitely.

The Supergate was destroyed before it was able to be activated, but Kallana was lost.

(SG1:Beachhead)