Supernovae seem easy enough to understand. Stars age, using up all of their fusion fuel and burst in a fiery display that helps to create the wide variety of elements seen throughout the universe. The trouble is, astronomers don’t yet actually understand the fine details that well.
Today astronomers got a bit closer to unravelling the mysteries of these stellar events, courtesy NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR). The X-ray observatory has been used to create the first-ever map of radioactivity in a supernova remnant.
Astronomers used NuSTAR to observe Cassiopeia A, an object formed from the remains of a huge star that went supernova. The event is still fairly young, with the light from the event having reached earth within just the past few hundred years.
Using the observatory researchers were able to map the location of the radioactive element titanium-44 throughout the supernova remnant. What they found was that the titanium is primarily located in “clumps” near the objects center.
“Stars are spherical balls of gas, and so you might think that when they end their lives and explode, that explosion would look like a uniform ball expanding out with great power,” said Fiona Harrison, co-author of a paper on the observations set to be published in Nature and a principal investigator for NuSTAR at the California Institute of Technology. “Our new results show how the explosion’s heart, or engine, is distorted, possibly because the inner regions literally slosh around before detonating.”
This observation calls into question several proposed models of how supernovae occur and could help astronomers determine exactly how the star that caused Cassiopeia A went supernova. The research may also help fine-tune computer models of supernovae that have failed to recreate the supernova remnants observed in reality.
“This is why we built NuSTAR,” said Paul Hertz, director of astrophysics at NASA. “To discover things we never knew – and did not expect – about the high-energy universe.”
Image via NASA/JPL-Caltech/CXC/SAO