The source of G1.9+0.3 was most likely a white dwarf star that underwent a thermonuclear detonation and was destroyed after merging with another white dwarf, or pulling material from an orbiting companion star. This is a particular class of supernova explosions (known as Type Ia) that are used as distance indicators in cosmology because they are so consistent in brightness and incredibly luminous. The explosion ejected stellar debris at high velocities, creating the supernova remnant that is seen today by Chandra and other telescopes. June 26, 2013.