Supernovae
© Romano Corradi and the Instituto de Astrofísica de Canarisa
Astronomers have provided the first-ever direct observations of a Type 1a supernova progenitor system. They collected evidence indicating that the progenitor system contained a red giant star. They also show that the system previously underwent at least one much smaller nova eruption before it ended its life in a destructive supernova.

Above, you see an artist's conception of a binary star system that produces recurrent novae, and ultimately, the supernova PTF 11kx. A red giant star (foreground) loses some of its outer layers though a stellar wind, and some of it forms a disk around a companion white dwarf star. This material falls onto the white dwarf, causing it to experience periodic nova eruptions every few decades. When the mass builds to the limit a white dwarf star can take, it explodes as a Type 1a supernova, destroying the white dwarf.