In the present work , the non-spherical dust grain characteristics of comet Hale-Bopp are studied using the T-matrix method and the modified power law distribution function .
It is found that the observed data fits very well with the power index ( \alpha ) = -3 .
The best fit values of complex refractive index ( n,k ) and the aspect ratio ( E ) at \alpha = -3 are calculated to be ( 1.382 , 0.035 , 0.936 ) and ( 1.379 , 0.041 , 0.936 ) at \lambda = 0.485 \mu m and 0.684 \mu m respectively .
Kerola & Larson ( K-L ) analysed the same comet using the T-matrix method and the power law distribution function ( \alpha = -3 ) , and found that the prolate grains can explain the observed polarization in a more satisfactory manner as compared to the other shapes .
But their analysis could not reproduce the negative polarization branch beyond scattering angle 157 ^ { 0 } .
However , the results obtained from the present work successfully generate the expected negative polarization curve beyond 157 ^ { 0 } and the fitting in this case is much better than K-L ’ s work .
So it is concluded from the present study that the use of modified power law distribution function ( with \alpha = -3 ) can fit the observed data in a better way , as compared to the power law distribution function used by previous authors .