Polarimetric studies of comet Levy 1990 XX

¹ Department of Physics, Karimganj College, Karimganj 788710, Assam, India e-mail: hs_das@rediffmail.com
² Department of Physics, Assam University, Silchar 788011, Assam, India e-mail: asokesen@sancharnet.in

Received: 23 April 2005
Accepted: 11 August 2006

Abstract

The spherical and non-spherical dust-grain characteristics of comet Levy 1990 XX are studied in this paper. Using T-matrix theory, a good theoretical fit to the polarisation data observed by Chernova and co-workers for comet Levy 1990 XX is reported in the present work. The calculated degree of linear polarisation (p) as a function of observed scattering angle produced by prolate spheroidal crystalline olivine particles with effective radius (m), effective variance (), and aspect ratio () are compatible with the comet's observed polarisation at m. After comparing the above result with the Mie theory result (m, ), it is found that prolate grains give the better fit to the observed polarisation data. Also, the negative polarisation behaviour of comet Levy 1990 XX is discussed.