A few weeks ago I posted an X-ray image of Cassiopeia A. recorded by the Chandra X-ray Observatory. Here’s a newer picture taken by NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR. In this false color image, blue indicates the highest energy of X-rays, while red and green show the lower end of NuSTAR‘s energy range, which overlaps with NASA’s high-resolution Chandra. X-ray light with energies between 10 and 20 keV (kiloelectron-volt) are blue; X-rays of 8 to 10 keV are green; and X-rays of 4.5 to 5.5 keV are red.
Astronomer’s believe that the first light from the stellar explosion that created Cassiopeia A reached Earth about 300 years ago, after traveling 11,000 years to get here. While the star is dead, its remains are bursting with action. The x-ray represented by the outer blue ring are caused by the shock wave from the supernova blast slamming into surrounding material, accelerating particles up to nearly the speed of light.
Image Credit: NASA