Earth Planets Space, Vol. 63 (No. 10), pp. 1041-1045, 2011
Nisha Katyal1, Ranjan Gupta1, and D. B. Vaidya2
1IUCAA, Post Bag 4, Ganeshkhind, Pune-411007, India
2ICCSIR, Ahmedabad 380006, India
(Received August 31, 2010; Revised June 16, 2011; Accepted June 17, 2011; Online published February 2, 2012)
A composite dust grain model which simultaneously explains the observed interstellar extinction, polarization, IR emission and the abundance constraints, is required. We present a composite grain model, which is made up of a host silicate oblate spheroid and graphite inclusions. The interstellar extinction curve is evaluated in the spectral region 3.4-0.1 μm using the extinction efficiencies of composite spheroidal grains for three axial ratios. Extinction curves are computed using the discrete dipole approximation (DDA). The model curves are subsequently compared with the average observed interstellar extinction curve and with an extinction curve derived from the IUE catalogue data.
Key words: Interstellar dust, extinction.