Cas A: Optical and X-ray
The aftermath of a cosmic cataclysm,
supernova
remnant Cassiopeia A (Cas A) is a
comfortable
11,000 light-years away.
Light from the Cas A supernova,
the death explosion of a massive star,
first reached Earth just 330 years ago.
Still expanding, the explosion's
debris cloud spans
about 15 light-years near the center of this
composite image.
The
scene combines color data of the
starry field and fainter filaments of material at optical energies
with image data from the orbiting NuSTAR X-ray telescope.
Mapped to false colors,
the X-ray data in blue hues trace the
fragmented outer boundary of the expanding
shock wave, glowing at energies up to
10,000 times the energy of the optical
photons.