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Paper: Probing Solar Nebula Using Polarization of Kuiper Belt Objects
Volume: 343, Astronomical Polarimetry: Current Status and Future Directions
Page: 194
Authors: Kolokolova, L.; Muinonen, K.; Boehnnhardt, H.; Bagnulo, S.; Barucci, A.; Rosenbush, V.
Abstract: Kuiper Belt Objects (KBOs) are believed to be pristine remnants of the solar nebula. and may be typical objects of protoplanetary disks. KBOs' location beyond the Neptune orbit allows to study their brightness and polarization opposition effects, known by their sensitivity to surface characteristics. We accomplished first polarimetric observations of one of the largest KBOs, 28978 Ixion. The polarimetric and photometric data were obtained in R filter for the phase angle range 0 — 1.3°. Ixion's polarization was found negative and reached −1.3%. So low a value has never been observed for solar-system bodies at these phase angles. Its brightness angular gradient, ≈ 0.2 mag/deg, is typical for other solar-system objects. We simulated Ixion's brightness and polarization using a light-scattering model by Muinonen (2004). The results of the simulations, combined with the observations and modeling of Ixion's BVRI photometry and spectrum, allows us to characterize its surface as covered by an areal, ‘spotty’ mixture of highly porous dark (absorptive) and less porous bright (icy) materials with the ratio 6:1.
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