NASA’s newest high-energy X-ray telescope has released two stunning images of a stellar explosion and ravenous black holes.
NuSTAR is the first high-energy X-ray telescope capable of producing eye candy. Two new images released this week at the American Astronomical Society showcase the telescope’s hundredfold increase in sensitivity over previous instruments.Cassiopeia A
The first image shows Cassiopeia A, the remnant of a 300-year-old stellar explosion. Since it’s only 1,000 light-years away, the supernova remnant has been studied in beautiful detail at many wavelengths. The Chandra X-ray Telescope, for example, has previously imaged Cassiopeia A at low X-ray energies. But examining Cassiopeia A at higher energies has never been possible before: previous high-energy X-ray telescopes haven’t had NuSTAR’s spatial resolution at these energies, so when the scopes looked at Cas A they would have seen only a fuzzy dot. NuSTAR, on the other hand, shows a panorama of the wispy tendrils that surround the central cinder of a star.
NuSTAR’s view provides more than just a pretty picture. The NuSTAR team is mapping out the presence of titanium-44, a radioactive element produced in supernova explosions. Stars make titanium-44 in a critical layer, inside of which the star collapses into a neutron star or black hole, and outside of which the star throws material off in a spectacular display. Once the NuSTAR team completes Cas A’s titanium-44 map, they’ll be able to reconstruct the original explosion.
Ultraluminous X-ray SourcesNuSTAR’s second image release shows the glow of two feeding black holes in nearby galaxy IC 342. The purple hot spots in the spiral arms are termed ultraluminous X-ray sources because they shine with an intensity that can’t easily be explained. They could be “intermediate-mass” black holes weighing thousands of Suns, or they could be ordinary stellar-mass black holes feeding at enormous rates. Either way, ULXs represent something exotic because astronomers don’t understand how intermediate-mass black holes grow, nor do they understand how ordinary stellar-mass black holes could feed at such high rates.
NuSTAR didn’t discover these ULXs — the Chandra X-ray Observatory did that. But NuSTAR adds crucial high-energy information that is going to help sort out which exotic mechanism is behind these brilliant X-ray sources.