Echoes of Ancient Supernovae Found

The echoes were found by comparing images of the Large Magellanic Cloud. The team looked for evidence of dark matter that might distort the light of stars in a transitory way by subtracting the common elements in each image. The research is part of a second-generation sky survey project called SuperMACHO, which builds on the discoveries of the MACHO project, which began at Lawrence Livermore National Laboratory in California in1989.

The image analysis revealed a small number of concentric, circular-shaped arcs, which are best explained as light moving outward over time, and being scattered as it encounters dense pockets of interstellar dust. Team members fit perpendicular vectors to the curves of each arc system. These were found to point backward toward the sites of three recent supernovae remnants that were found previously, via their X-ray glow, by the orbiting Chandra X-ray observatory.

According to Armin Rest of the National Optical Astronomy Observatory (NOAO), relatively simple mathematics can now be used to determine how old the objects are. Theoretically, astronomers can investigate what type of supernova occurred by splitting the light echo into a spectrum. They can also use supernova light echoes to measure the structure and nature of the interstellar medium. A supernova blast can illuminate the dust and gas between the stars which are invisible without a light source.