Nahanas was a rogue comet that travelled through space near Bajor in the 2370s. The crust of the comet was composed of ultritium and its surface was marked with jagged crystalline rock formations.
In January 2377, Taran'atar, while heading to Harkoum aboard the USS Euphrates, placed the runabout's microtorpedo ordnance on the surface of Nahanhas. He also transported Prynn Tenmei's combadge down to the comet, which the crew of the USS Defiant detected. When they lowered their shields and attempted to beam Prynn aboard, the explosives detonated, destroying the comet. The Defiant was badly damaged by the debris and the shockwave from Nahanas, leaving the starship disabled and adrift. They Defiant was unable to continue the pursuit of Taran'atar for several hours. (DS9 novel: Warpath)