Remarks about the thermodynamics of astrophysical systems in mutual
  interaction and related notions
  General aspects about the thermodynamics of astrophysical systems are
discussed, overall, those concerning to astrophysical systems in mutual
interaction (or the called \emph{open astrophysical systems}). A special
interest is devoted along the paper to clarify several misconceptions that are
still common in the recent literature, such as the direct application to the
astrophysical scenario of notions and theoretical frameworks that were
originally conceived to deal with extensive systems of the everyday practice
(large systems with short-range interactions).
