The trilithium torpedo was created by Doctor Tolian Soran, an El Aurian scientist who had an encounter with the Nexus in 2293. Soran searched for a safe method of re-entering the Nexus for decades; eventually he hit upon the idea of altering its course to bring it close to a planetary surface. This would allow him to wait on the planet in safety. In order to alter the course of the Nexus, Doctor Soran needed to significantly alter the mass of stars at certain points close to its course. The trilithium torpedo was his solution to this problem.1
Precise details of the trilithium weapon are uncertain, but members of the Enterprise-D crew were able to scan a torpedo at close range.1 Subsequently the ship was able to record detailed sensor information when the Amargosa system was destroyed by Doctor Soran. Those records indicate that the torpedo initially causes a massive flare-up in the stars output. This initial burn lasts for some seven seconds, releasing some 4.2 x 1046 Joules and consuming approximately 23% of the mass of the star. This process produces a level 12 shockwave, powerful enough to destroy everything in the entire solar system. It also significantly alters the gravitational forces in the region.1
Immediately subsequent to the primary energy release, a quantum implosion occurs within the star. This causes a very rapid breakdown in all remaining fusion processes; starved of the thermal pressure that normally holds a star inflated, the remnants of the Amargosa star collapsed under their own weight1 into a black dwarf.
Doctor Soran attempted to launch a further weapon at the Veridian sun, but was prevented in doing so by two Starfleet officers. This weapon was destroyed together with all of its supporting facilities when it exploded on launching.1
The Federation has classified its information concerning trilithium weapons and outlawed any attempt at production, in line with the laws against the production and use of weapons of mass destruction. However, it is likely that detailed research is proceeding.