A Bela-Neutron device was a piece of technology that was theorized by Professor Edvard Bela.
The basis of the machine was one of a number of the scientist's conceptual breakthroughs that stated that millions of such devices were capable of absorbing heavy particles from a star, like hydrogen and helium nuclei. The devices re-emit neutrinos plus electrons and positrons. The neutrinos do not interact with anything except for neutrino collectors positioned in the system, so most of the energy was wasted away uselessly. This left little energy present to hold the sun's diameter apart against the crushing pull of gravity. The end result was the sun collapsing and bringing about a large explosion.
While theoretical, the crew of the Federation starship USS Voyager discovered working Bela-Neutron devices that were made by the ancient Furies who placed it within their home star system in order to use it to create an artificial wormhole to the Alpha Quadrant. (VOY novel: The Final Fury)