Polarimetry of Dust in Optically Thin Clouds: Observations and Experimental Simulations of Cometary and Interplanetary Dust
Abstract
Remote polarimetric observations are used to tentatively infer the physical properties of the dust particles in cometary and interplanetary environments. To interpret the results, numerical and experimental simulations are necessary. Light scattering measurements on levitating particles with the PROGRA2 experiment -in dedicated microgravity flights or in the laboratory for low-density particles- provide relevant simulations of the scattering properties of real particles, which can present large size distributions and a large variety of structures and materials (Renard et al., 2002; Hadamcik et al., 2009). Previous systematic experiments, together with numerical models and laboratory analysis of cosmic particles (e.g. Stardust samples) allow to optimize dust particles' properties -such as their structures, sizes, size distributions, and silicate to organics ratios- (Hadamcik et al. 2007a; Zubko et al., 2009; Lasue et al., 2010). We present intensity and polarization images of cometary comae providing evidence for changes in the polarization properties in the internal regions of the coma, linked to the variation of particles properties with nucleus distance and/or rotation phase (Hadamcik et al., 2007a; Hadamcik et al., 2013a; 2013b) and preliminary results of 2013 observations. Associated experimental simulations help us to interpret how particles evolve within different coma regions and at different solar distances (Hadamcik et al. 2007b; 2009; 2011). We expect in situ confirmation of our results during the Rosetta mission to comet 67P/Churyumov-Gerasimenko in 2014-2015 (Hadamcik et al., 2010). Analyses of observations of the zodiacal light scattered by the interplanetary dust cloud particles have shown local polarisation changes with the solar distance (Levasseur-Regourd et al., 2001). Such changes are interpreted through numerical models to be related to variations in the composition and physical properties of the particles through various processes including thermal degradation (Lasue et al., 2007; Levasseur-Regourd et al., 2007). This interpretation is now validated on real mixtures of particles corresponding to the zodiacal dust composition at different solar distances. We acknowledge CNES and ESA support for the microgravity flights and experimental work References Hadamcik and Levasseur-Regourd (2007a) DPS 39,53.19 Hadamcik et al. (2007b) Icarus 190, 660. Hadamcik et al. (2009) LS Rev 4, Kokhanovsky ed., 31 Hadamcik et al. (2010) AandA 517,A86 Hadamcik et al. (2011) In: Polarimetric detection, characterization, and remote sensing (Mishchenko et al.), NATO series for peace and security, 137 Hadamcik et al. (2013a) Icarus 222, 774 Hadamcik et al. (2013b) M&PS in press Lasue et al. (2010) Icarus 199, 129 Lasue et al. (2007) AandA 473, 641 Levasseur-Regourd et al. (2001) In: Interplanetary dust, Grün et al. Eds, 57 Levasseur-Regourd et al. (2007) PSS 55,1010 Renard et al. (2002) Appl Opt 44, 609 Zubko et al. (2009) JQSRT 110, 1741
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.P42B..09H
- Keywords:
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- 6015 PLANETARY SCIENCES: COMETS AND SMALL BODIES Dust;
- 6094 PLANETARY SCIENCES: COMETS AND SMALL BODIES Instruments and techniques;
- 6040 PLANETARY SCIENCES: COMETS AND SMALL BODIES Origin and evolution;
- 6210 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS Comets