Supernova Factory NGC 2770 . ... Instituto de Astrof sica de Andaluc a ( CSIC ), University of Hertfordshire Explanation: The stellar explosions known as supernovae are among the most powerful events in the universe. Triggered by the collapsing core of a massive star or the nuclear demise of a white dwarf, supernovae occur in average spiral galaxies only about once every century. But the remarkable spiral galaxy NGC 2770 has lately produced more than its fair share. ...