Tal'lhnor Gates was a binary star system containing a main sequence star and a black hole that was near the Romulan border and was the Klingon Empire's primary energy production facility until 2291. During the Klingon Civil War of 2292, Melkor, son of G'Iogh offered the Romulan Star Empire possession of several important systems, including the Tal'lhnor Gates, in exchange for support to attain leadership of the Imperial throne.
Unfortunately, the star went supernova when Melkor ordered Brigadier K'mak to detonate a powerful gravitational attenuation device near the event horizon of the black hole as an act of spite, rather than let it fall into General Chang's hands. the Gates star detonated, flooding the system with radiation and forming a new planetary nebula around the black hole. (TOS video game: Klingon Academy)