The Effect of Orientation of Non-Spherical Particles on Interstellar Extinction.

An investigation is made of the effect of orientation of non-spherical particles on the interstellar reddening-curve. An approximate calculation of the scattering by non-spherical particles is applied to a model dust cloud. It is predicted that there should be significantly greater extinction in the ultraviolet relative to the visible for stars viewed along magnetic-field lines as compared with those viewed across. A preliminary comparison with existing data indicates qualitative confirmation of the prediction.