The Hobus nebula was a massive stellar nebula in the late 24th and early 25th centuries. It was created in 2387 when the Hobus star went supernova, sending out a shock wave at multi-warp speeds, leading to the destruction of Romulus. Luckily, however, the star was collapsed by Ambassador Spock, using Red matter to create an artificial Black Hole. (TNG comic: "Star Trek: Countdown")