Resolution of compact knots in Cassiopeia A

Observations of the young supernova remnant Cassiopeia A at a wavelength of 2 cm have resolved small knots. The flux density of these knots decays on a 1/e time scale of about 14 yr. This is faster than the decay of the smooth features. The pressure in these knots can be estimated at 4 x 10 to the 7th dynes/sq cm. This is somewhat greater than the pressure within the smooth component of the supernova remnant.