The planet about three light years from Bilana III that was to catch and disperse the experimental soliton wave in 2368, and which was nearly destroyed when the wave ran out of control.
Lemma II appears in the Next Generation episode New Ground. Doctor Ja'Dar's team on Bilana III plans to push an unpowered test ship to warp speed on a soliton wave, with a sister station on Lemma II generating a scattering field to dissipate the wave on arrival.
The Enterprise monitors the test. The wave proves unstable, destroys the test ship, damages the Enterprise and then gains energy and speed as it travels, until it is certain to overwhelm the scattering field and devastate the colony.
With too little time for an evacuation, Picard takes the ship straight through the wave to get ahead of it and fires photon torpedoes to break it up. The dangerous manoeuvre also traps Worf's son Alexander in a burning laboratory.