Astronomers might have found the long-lost cinder of a conflagration that left them spellbound more than three decades ago.

In 1987, researchers witnessed a massive star in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, collapse under its own weight and then explode as a supernova. At a mere 51,400 parsecs (168,000 light years) from Earth, it was the closest observed supernova since the 1600s.

Some of the matter in the core should have compressed to form a neutron star, a body only about 20 kilometres wide but more massive than the Sun. Researchers have tried to locate such a remnant inside the cloud of dusty debris left by the explosion, but so far all efforts have failed.

Phil Cigan at Cardiff University, UK, and his collaborators scanned the region with the Atacama Large Millimeter/submillimeter Array in northern Chile, and found an unusually hot region in the cloud. The researchers say that this feature, which they nicknamed the blob, is evidence of the neutron star heating its surroundings.