R. Domingueztenreiro et Ma. Gomezflechoso, DYNAMICAL FRICTION FOR COMPOUND BODIES, Monthly Notices of the Royal Astronomical Society, 294(3), 1998, pp. 465-477
In the framework of the fluctuation-dissipation approach to dynamical
friction, we derive an expression giving the orbital energy exchange e
xperienced by a compound body, as it moves, interacting with a non-hom
ogeneous discrete background. The body is assumed to be composed of pa
rticles endowed with a velocity spectrum and with a non-homogeneous sp
atial distribution. The Chandrasekhar formula is recovered in the limi
t of a point-like satellite with zero velocity dispersion and infinite
temperature moving through a homogeneous infinite medium. In this sam
e limit, but dropping the zero satellite velocity dispersion (sigma(s)
) condition, the orbital energy loss is found to be smaller than in th
e sigma(s) = 0 case by a factor of up to an order of magnitude in some
situations.