Comment on "On physical interpretation of the Poynting-Robertson effect"
  In response to the comments of astro-ph/0006426 on Srikanth (Icarus 1999), we clarify, and thereby justify, the definition of Poynting-Robertson drag adopted in the latter. We confirm that dust absorption is a necessary condition while re-emission is neither necessary nor sufficient for the inspiralling of a rest-isotropically emitting dust. 
R. Srikanth