A Herschel study of Planetary Nebulae
  We present Herschel PACS and SPIRE images of the dust shells around the planetary nebulae NGC 650, NGC 6853, and NGC 6720, as well as images showing the dust temperature in their shells. The latter shows a rich structure, which indicates that internal extinction in the UV is important despite the highly evolved status of the nebulae. 
G. C. Van de Steene, K. M. Exter, P. A. M. van Hoof, T. L. Lim, M. J.   Barlow, M. Matsuura, T. Ueta, and the MESS Consortium
astro-ph.SR