2.1. The Dust Component
The physical properties and the size distribution of
the interstellar dust grains have been fixed to a very widely
accepted variety for all our models.
An equal mixture (50% : 50%) of Graphite and Astronomical
Silicate grains, and a gas to dust ratio of 100:1 by mass,
have been considered. All physical properties
of the grains, viz., absorption, scattering
efficiencies and linear anisotropy factor have been taken
from Draine & Lee
(1984) and
Laor & Draine (1993).
Averaging over 29 discrete sizes have been performed,
following a size distribution of n(a)da ~
a-mda,
amin a
amax, with m = 3.5
(Mathis et al., 1977).
The lower and upper limits of the
grain size distribution, amin (0.01 µm)
and amax
(0.25 µm), have been taken from
Mathis et al. (1983).