230 likes | 248 Vues
Explore the formation of primitive grain aggregates in nebula dust through systematic investigations in a microwave analogue laboratory. Study color generation, particle interactions, and micron-scale structures.
E N D
NEBULA DUST: PRIMITIVE GRAIN AGGREGATES OR RECONDENSED? Bo Gustafson Collaborators: Ashley Espy, Univ. of Florida Ludmilla Kolokolova, Univ. of Maryland Yu-Lin Xu, NASA/JSC
Silicate and organics in Visual = Plastics in Microwave ADVANTAGES / LIMITATIONS - Analogue materials are grey - One particle, one geometry at a time - Scaling = NO APPROXIMATION - Systematic Investigations
Color through Red and Blue Filters Color Scattering Angle [Degrees] Blue color is usually not observed. Intensity Scattering Angle [Degrees]
Color through Red and Blue Filters Color Scattering Angle [Degrees] Denser = redder. Dust aggregates need not be dense or very large for interaction to be important Intensity Scattering Angle [Degrees]
HOW COLOR IS CREATED: INTERACTION VOLUME DEPENDS ON WAVELENGTH Denser = redder. Dust aggregates need not be dense or very large for interaction to be important 1 micron
OBSERVED Polarimetric color for cometary dust is red but blue for zodiacal light. Polarization through Red and Blue Filters Polarimetric Color Scattering Angle [Degrees] Polarization Scattering Angle [Degrees]
OBSERVED Can be cometary but not Zodiacal Polarimetric color for cometary dust is red but blue for zodiacal light. Polarization through Red and Blue Filters Polarimetric Color Scattering Angle [Degrees] Polarization Scattering Angle [Degrees]
OBSERVED Color for cometary dust and zodiacal dust is mostly red. Color Scattering Angle [Degrees] Intensity Scattering Angle [Degrees]
OBSERVED Color for cometary dust and zodiacal dust is mostly red. Color Scattering Angle [Degrees] Intensity Larger = redder. Scattering Angle [Degrees]
Polarimetric Color Scattering Angle [Degrees] Polarization Still looks like cometary dust (red) Scattering Angle [Degrees]
OBSERVED Color for cometary dust and zodiacal dust is mostly red. Color Scattering Angle [Degrees] Intensity Scattering Angle [Degrees]
OBSERVED Color for cometary dust and zodiacal dust is mostly red. Color Scattering Angle [Degrees] Intensity Look redder Scattering Angle [Degrees]
OBSERVED Polarimetric color for cometary dust is red but blue for zodiacal light. Polarimetric Color Scattering Angle [Degrees] Polarization Scattering Angle [Degrees]
OBSERVED Polarimetric color for cometary dust is red but blue for zodiacal light. Polarimetric Color Scattering Angle [Degrees] Polarization Look bluer Scattering Angle [Degrees]
“Comet” aggregate 1.0 Sphere 0.1 1.4 1.6 1.0 1.2 280 K isotherm [AU] 0.01
CONCLUSIONS - Interactions inside aggregates generate colors - Large aggregates can behave as though they were made of larger substructures than they really are. - “Asteroid” / “comet” particles differences in polarimetric color - “Asteroid” / “comet” particles trends are as observed • Micron scale structure in aggregates may preserve memory of aggregation processes
OBSERVED Color for cometary dust and zodiacal dust is mostly red. Color Scattering Angle [Degrees] Intensity Look redder Scattering Angle [Degrees]
OBSERVED Polarimetric color for cometary dust is red but blue for zodiacal light. Polarimetric Color Scattering Angle [Degrees] Polarization Scattering Angle [Degrees]
OBSERVED Polarimetric color for cometary dust is red but blue for zodiacal light. Polarimetric Color Scattering Angle [Degrees] Polarization Scattering Angle [Degrees]