|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|5426999||1397241||2018||6 صفحه PDF||ندارد||دانلود کنید|
â¢The ground-based observations of near-Earth asteroids were carried out.â¢The position of polarization maximum depends on asteroid's albedo.â¢The computer simulations of the polarimetrical properties of asteroids were done.â¢The influence of the refractive indices on the linear polarization maximum is studied.
The ground-based observations of near-Earth asteroids at large phase angles have shown some feature: the linear polarization maximum position of the high-albedo E-type asteroids shifted markedly towards smaller phase angles (Î±maxÂ âÂ 70Â°) with respect to that for the moderate-albedo S-type asteroids (Î±maxÂ âÂ 110Â°), weakly depending on the wavelength. To study this phenomenon, the theoretical approach and the modified T-matrix method (the so-called Sh-matrices method) were used. Theoretical approach was devoted to finding the values of Î±max, corresponding to maximal values of positive polarization Pmax. Computer simulations were performed for an ensemble of random Gaussian particles, whose scattering properties were averaged over with different particle orientations and size parameters in the range XÂ =Â 2.0Â ...Â 21.0, with the power law distribution Xâ¯ââ¯k, where kÂ =Â 3.6. The real parts of the refractive index mr were 1.5, 1.6 and 1.7. Imaginary part of refractive index varied from miÂ =Â 0.0 to miÂ =Â 0.5. Both theoretical approach and computer simulation showed that the value of Î±max strongly depends on the refractive index. The increase of mi leads to increased Î±max and Pmax. In addition, computer simulation shows that the increase of the real part of the refractive index reduces Pmax. Whereas E-type high-albedo asteroids have smaller values of mi, than S -type asteroids, we can conclude, that value of Î±max of E-type asteroids should be smaller than for S âtype ones. This is in qualitative agreement with the observed effect in asteroids.
Journal: Journal of Quantitative Spectroscopy and Radiative Transfer - Volume 204, January 2018, Pages 88-93