Interstellar extinction by spheroidal dust grains

摘要: Observations of interstellar extinction and polarization indicate that the medium consists aligned non- spherical dust grains which show variation in curve for wavelengths ranging from NIR to UV. To model polarization, one cannot use conventional Mie theory assumes as solid spheres. We have used a T-matrix based method computing efficiencies spheroidal silicate graphite different shapes (axial ratios) sizes these evaluate wavelength range 3.4−0.1 µm. A best fit linear combination not very large axial ratio, fits observed reasonably well. calculate volume factor Vc, is an important parameter point view cosmic abundance, grain models reproduce curve. find shape does affect factor. Finally we also studied spheroids. The results affects considerably various orientation angles