In Star Trek: The Next Generation, what mechanism lets a starship eject its dangerous warp core?

In Star Trek: The Next Generation, the warp core ejection system lets a starship eject its dangerous warp core.

A warp core contains the matter–antimatter reaction that supplies enormous power for propulsion and ship systems. If the reaction becomes unstable, the crew may separate the core from the vessel and send it into space before an explosion damages the ship.

The system is shown repeatedly on the Enterprise-D and other Federation starships. It is an emergency safeguard, not a routine method of shutting down the engines. Ejecting the core can save the ship, but it also leaves the vessel without its main power source and may create a hazard nearby.

The phrase is sometimes shortened in dialogue to “eject the core.” That wording refers to the same emergency procedure. It should not be confused with the antimatter containment system, which keeps fuel isolated, or with the core itself, which is the reactor rather than the ejection mechanism.