A solar probe was a type of probe designed to study stars at close distance for scientific research. They could be modified to crash into a sun. The Egg was an example of a solar probe.
In 2371, Tolian Soran, an El-Aurian scientist, utilized a solar probe outfitted with trilithuim to destroy the Amargosa star which it creates a level 12 shock wave. He later attempted to perform the same action on the Veridian star, but was stopped by Jean-Luc Picard and the crew of the USS Enterprise, along with James T. Kirk. (Star Trek Generations)