Cassiopeia A (Cas A) is what remains of a supernova in the constellation Cassiopeia. Cas A is a massive star that exploded in a supernova more than 11,000 years ago and has long confounded astronomers and scientists.

NASA’s Chandra X-ray Observatory took images (top) of Cassiopeia A using low-energy X-rays which showed certain elements, such as iron, that were heated by the shock waves released in the explosion of Cas A. The iron is seen mainly in the outer portions of the star.

More recently, NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR has brought new information about Cas A to light. It is the first telescope capable of creating maps of radioactive material and take pictures of radioactive titanium-44, which gives off high-energy X-rays that the telescope was designed to capture.

So does Cassiopeia A have iron at its core?