Internal extinction: ai
The dust extinction within galaxies in the B-band, ai [mag] is
computed after Bottinelli
et al. 1995, A&A296, 64.
This formula is a function of the morphological type, t,
and of the apparent flattening, logr25.
where m0 is the corrected magnitude and mi is the
R is the axis ratio derived from logr25
k is the bulge to disk ratio and depends on morphological type as follows: k=0.754*10(-0.2*t),
if k >1 then k=1 (Simien and de Vaucouleurs)
K is the coefficient dlogD/db (where D is the isophotal diameter at surface brightness b).
It depends on the morphological type t as:
K = 0.12-0.007*t if t < 0.
K = 0.094 if t >= 0.
and C is defined as (dlogD/dlogR) and has the fixed value of 0.04