Some implications of the introduction of scattered starlight in the spectrum of reddened stars

Abstract

This paper presents new investigations on coherent scattering in the forward direction (orders of magnitude; conservation of energy; dependence of scattered light on geometry and wavelength), and on how scattered light contamination in the spectrum of reddened stars is possibly related to as yet unexplained observations (the diminution of the 2200 A bump when the obscuring material is close to the star, the difference between Hipparcos and photometric distances). This paper then goes on to discuss the fit of the extinction curve, a possible role of extinction by the gas in the far-UV, and the reasons of the inadequacy of the Fitzpatrick and Massa [ApJSS, 72 (1990) 163] fit.