The NuSTAR data also reveals a flaring source of high-energy X-rays, called an ultraluminous X-ray source, or ULX. This object, which appears as a blue spot near the hotter, central region of the galaxy, is either a black hole or a dense, dead star, called a neutron star, feeding off a partner star. The flare is thought to be the result of a change in the object’s feeding patterns.
The other orange and reddish points are likely additional X-ray-generating pairs of stars located throughout the galaxy.
In this image, red shows low-energy X-ray radiation (3 to 7 kiloelectron volts), green is medium energy (7 to 10 kiloelectron volts), and blue is high energy (10 to 20 kiloelectron volts).