snr0519 While astronomers have seen the debris from scores of exploded stars in the Milky Way and nearby galaxies, it is often difficult to determine the timeline of the star’s demise. By studying the spectacular remains of a supernova in a neighboring galaxy using NASA telescopes, a team of astronomers has found enough clues to help wind back the clock. The supernova remnant called SNR 0519-69.0 (SNR 0519 for short) is the debris from an explosion of a white dwarf star. After reaching a critical mass, either by pulling matter from a companion star or merging with another white...