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[Sky Map]                         CASSIOPEIA A: Supernova Remnant
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[Chronological Listing]           What Do These Images Tell Us?
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[Search]                             [Cas A in X-ray]   [Cas A - Optical]   [Cas A - Infrared]    [Cas A - Radio]


 [X-ray Label]    [Cas A in X-ray]  These images show Cas A as viewed by four
				    different types of telescopes. The X-ray
		image of the Cassiopeia A supernova remnant on the left is the
		official first light image of the Chandra X-ray Observatory. The
		5,000 second image was made with the Advanced CCD Imaging
		Spectrometer (ACIS). Two shock waves are visible: a fast outer
		shock and a slower inner shock. The inner shock wave is believed
		to be due to the collision of the ejecta from the supernova
		explosion with a circumstellar shell of material, heating it to
		a temperature of ten million degrees. The outer shock wave is
		analogous to an awesome sonic boom resulting from this
		collision. The bright object near the center may be the long
		sought neutron star or black hole that remained after the
		explosion that produced Cas A.

 [Optical Label]    [Cas A - Optical]  The optical image of Cas A shows matter
				       with a temperature of about ten thousand
		  degrees. Some of these wisps high concentrations of heavy
		  elements and are thought to be dense clumps of ejected stellar
		  material.

 [Infrared Label]    [Cas A - Infrared]  The infrared image of Cas A shows dust
					 grains that have been swept up and
		   heated to several hundred degrees by the expanding hot gas.
		   It is not known whether the dust grains were ejected by the
		   star millions of years before it exploded or during the
		   explosion.

 [Radio Label]    [Cas A - Radio]  Cas A gets its name from radio astronomers,
				   who ‘rediscovered' it in 1948 as the
		strongest radio source in the constellation of Cassiopeia. About
		5 years later optical astronomers found the faint wisps, and it
		was determined that Cas A is the remnant of an explosion that
		occurred about 300 years ago. The radio emission comes from high
		energy electrons moving in large spirals around magnetic field
		lines of force.

[Link to First Chandra Targets]
Cas A in Context              Cas A Index
Constellation                 More on Supernovae
Cassiopeia                    Supernova Word
Locate Cas A in the           Search
Sky                   [Image] PKS 0637-752
What Do the Images            Note on Cosmic
Tell Us?                      Distances
Cas A Fact Sheet
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                              Revised: 09/01/99