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A.Ch. Levasseur-Regourd (Univ. Paris / Aeronomie), E. Hadamcik (Aeronomie)
Information about dust scattering properties is now available for a fairly large amount of comets. It allows to point out differences between different regions in the coma, as well as differences in the polarization degree for a given phase angle (greater than about 40°) and a given wavelength range. Besides, it can be noticed that the polarization (for a given phase angle above 40°) usually increases with the wavelength, and that the slope of increase is greater for higher wavelengths in the visible and near infrared domains.
However, the trend is rather different in some jet like structures, and quite different in the vicinity of the nucleus. This behavior of the polarization, so-called its color, will be interpreted through light scattering measurements. Such measurements, performed on various samples, including very fluffy and porous particles, provide some clues to the structure of the cometary dust particles.
We acknowledge PNP Planetologie for the observations and CNES for the laboratory measurements under microgravity conditions.
The author(s) of this abstract have provided an email address for comments about the abstract: aclr@aerov.jussieu.fr