Expanding bubbles of hot gas are all that remains of a star that appears to have exploded twice, according to a new study. Supernova Remnant 0509-67.5 is in the Large Magellanic Cloud, a companion galaxy to the Milky Way. It exploded several hundred years ago as seen from Earth. The new study found two shells of calcium atoms in the debris (coded in blue in this false-color image). The shells support theoretical models that suggest the star exploded twice. The star was a white dwarf, which is the dead core of a once Sun-like star. The white dwarf pulled helium gas from the surface of a companion star. When enough helium accumulated on the white dwarf, the helium exploded. That squeezed and heated the core of the white dwarf, which then exploded even more violently, destroying the entire star. [ESP/P. Das et al. Background stars (Hubble): K. Noll et al.]