Characterization of aerosols in the detached haze layer of Titan

The aim of this work is to deduce physical characteristics of the aerosols that compose the thin detached haze layer of Titan, for which the compositi on and origin are currently unknown. We have used four images at three diff erent phase angles and three different wavelengths where the detached haze clearly appears. The low optical path in the layer permits assumptions that greatly simplify the treatment and allow us to consider the scattered inte nsity as the product of the scattering cross section, the phase function at the considered phase angle, and the number of aerosols, Physical arguments are given to support fractal aerosols in the detached haze, and we investi gate a wide range of monomer radii, monomer numbers, and imaginary refracti ve indexes. This study yields information about the spectral variation of t he refractive index for the detached haze tholins that are clearly differen t from those for the main haze. On the other hand, no firm values are given for the monomer radius and number, but these two parameters are strongly l inked through a simple relation. (C) 2000 Academic Press.