The smash hit from 1987 (Image: ESO)

The flash of a recent supernova is helping create a 3D map of a nearby galaxy.

In January astronomers rushed to their telescopes to observe 2014J, the closest supernova in 27 years, as it burst into view. Now Arlin Crotts of Columbia University in New York City is watching the light from this stellar explosion echo around its host galaxy M82, also known as the Cigar Galaxy.

Although we normally associate echoes with sound, other waves also echo – radio echoes are the principle behind radar. Supernovas produce light in all directions that bounces off dust in the surrounding region of space. Measuring the different times it takes for these light echoes to reach Earth gives a map of the dust in M82, which is 11.4 million light years away.


Dust occupies a large volume of most galaxies, and mapping it can give researchers a deeper understanding of galactic structure. Crotts has used the Hubble Space Telescope to watch the echoes as they appeared in the sky. “You have this really detailed 3D map, all the way over in some distant galaxy where there is really no other way to make such a map,” he says.

It is normally difficult to see light echoes because most supernovae are extremely far from Earth, but 2014J is the second-closest ever, after the 1987 supernova in the Large Magellanic Cloud. “It was always expected that M82 would be a good target for searching for light echoes,” says Stephen Fossey of University College London, who first spotted the supernova. “This kind of work is certainly important for probing the dust environment.”

Reference: arxiv.org/abs/1409.8671