Cassiopeia A (Cas A), which is located about 11,000 light-years from Earth, is the most studied nearby supernova remnant.
When the original star ran out of fuel, it collapsed onto itself and blew up as a supernova, possibly briefly becoming one of the brightest objects in the sky.
Although scientists think that this happened around the year 1680, there are no verifiable historical records to confirm this.
Previously astronomers had used NASA’s NuSTAR telescope to discover an unstable isotope of titanium — titanium-44 — in different locations in Cas A.
“Scientists think most of the titanium that is used in our daily lives — such as in electronics or jewelry — is produced in a massive star’s explosion,” said Dr. Toshiki Sato, an astronomer at Rikkyo University.