The remains of this supernova are enveloped in a shell of its own ejecta, a funeral shroud hinting at the star’s explosive end.

Astronomers pieced together 150 hours of observations using the space-based Chandra X-ray Observatory to produce this view of the supernova G21.5-0.9, which sits about 20,000 light years away. Supernovas are stellar explosions and can generate a massive shockwave that plows through interstellar space and heats gas into the millions of degrees, ultimately emitting X-rays.

Although the supernova seen here was first discovered 30 years ago, it took Chandra’s X-ray eye to discern its outer shell of hot gas, which was cast out when its home star exploded. Not all supernovas leave behind detectable signs of an outer shell, prompting astronomers to postulate that some sort of weaker explosion may be at work. But with Chandra’s findings, that seems unlikely, researchers said.

Chandra observed this supernova between Aug. 23, 1999 and March 29, 2004, though the image was released on April 19, 2005. Astronomers estimate that the star that produced this supernova was once about 10 times as massive as the Sun.

-- SPACE.com Staff

Credit: NASA/CXC/U. Manitoba/H. Matheson & S. Safi-Harb.