Extinction in inhomogeneous clouds

Abstract

An investigation is carried out on the effects of the spatial distribution of dust in the line of sight to an extended source on observed extinction. Consideration is given to a continuous dust cloud layer and one divided into clumps. An analytical relation is defined between the dust distribution parameters and the extinction. The extinction curve is analyzed as a function of wavelength, particularly with respect to the 2200 A bump and the H-alpha/H-beta ratio. A technique is derived for determining both the intrinsic extinction properties and geometric dust distribution using the observed extinction curve and is illustrated with the H II region K3-50. Extinction for the region is projected to be caused by both interstellar and local dust.