Astronomers are getting a closer look at what happens in the heart of an exploding star.
This image was collected by NASA’s x-ray NuStar telescope.
It's the first to map radioactive material in a so-called supernova.
The blue color highlights the radioactive material.
Blown-out pieces from a massive exploding star produced this remnant known as "Cassiopeia A."
It is located about 11 thousand light years away from earth.
Astronomers found radioactive titanium-44, an unstable isotope, was produced in the heart of the exploding star.
The energy from that eventually blew off the star's outer layers.
The full results are published in the journal Nature.