Lemma II is a planet where a Federation colony is located.
In 2368, this planet was the intended destination of an experimental soliton wave generated from Bilana III, three light years away. The Lemma II facility was intended to generate a scattering field to disperse the wave. However, the wave destabilized and accelerated out of control, threatening to destroy most of Lemma II. Fortunately, the USS Enterprise-D disrupted the wave before it arrived. (TNG: "New Ground")