Supernova
A supernovea is a stellar explosion involving a star at the end of its life, when it's iron core starts colapsing due to gravity or when two stars merges together and became unstable. Then it will collapse and in so doing will release a huge focused beam of charged particles from it's poles. Then based on the remnants left behind the star will either became a pulsar or colapse into even denser object- a black hole.
While many supernovae have been seen in nearby galaxies, they are relatively rare events in our own galaxy. The last to be seen was Kepler's star in 1604. This remnant has been studied by many X-ray astronomy satellites, including ROSAT. There are, however, many remnants of Supernovae explosions in our galaxy, that are seen as X-ray shell like structures caused by the shock wave propagating out into the interstellar medium. Another famous remnant was observed in 1054, when Chinese astronomers recorded a supernova so bright that it was visible during the day. The explosion left behind a pulsar and a huge cloud of gas and dust known as the Crab Nebula, which still can be seen today with its pulsar rotating 30 times a second and emitting X-rays in a fashion similar to a lighthouse. [1].