Multiple scattering in reflection nebulae. I. A Monte Carlo approach

A method is described which permits the calculation of the surface brightness distribution on a plane-parallel reflection nebula of uniform density, illuminated by a single star located in front of, behind, or arbitrarily inside the nebula. The multiple scattering problem is solved by the Monte Carlo technique in a three-dimensional simulation. The models are completely parametrized by describing particle properties by their single-scattering albedo and by an analytic phase function with one or three parameters. The computations are thus independent of wavelength or assumed size distributions of the scattering particles and are therefore particularly suited for the analysis of observations of the surface brightness of reflection nebulae in spectral regions, such as the ultraviolet, for which detailed particle models are still uncertain