A Herschel PACS and SPIRE study of the dust content of the Cassiopeia A
  supernova remnant
  Using the 3.5-m Herschel Space Observatory, imaging photometry of Cas A has
been obtained in six bands between 70 um and 500 um with the PACS and SPIRE
instruments, with angular resolutions ranging from 6 to 37". In the outer
regions of the remnant the 70-um PACS image resembles the 24-um image Spitzer
image, with the emission attributed to the same warm dust component, located in
the reverse shock region. At longer wavelengths, the three SPIRE bands are
increasingly dominated by emission from cold interstellar dust knots and
filaments, particularly across the central, western and southern parts of the
remnant. Nonthermal emission from the northern part of the remnant becomes
prominent at 500 um. We have estimated and subtracted the contributions from
the nonthermal, warm dust and cold interstellar dust components. We confirm and
resolve for the first time a cool (~35 K) dust component, emitting at 70-160
um, that is located interior to the reverse shock region, with an estimated
mass of 0.075 Msun.
