scholarly journals Light Scattering as a Clue to Cometary Dust Structure

2005 ◽  
Vol 13 ◽  
pp. 498-500 ◽  
Author(s):  
A. Chantal Levasseur-Regourd ◽  
E. Hadamcik ◽  
J. Lasue
Keyword(s):  
Light Scattering ◽  
Physical Properties ◽  
Phase Angle ◽  
Linear Polarization ◽  
Dust Structure ◽  
Cometary Dust ◽  
Microgravity Conditions

AbstractThe linear polarization of comets depends upon the cometary dust physical properties, as well as upon the phase angle and the wavelength. The observed similarities and discrepancies provide drastic constraints on the physical properties of the dust. A series of measurements of light scattering properties on clouds of particles and of the aggregates they form under microgravity conditions should allow the interpretation of the observations in terms of physical properties of the dust.

scholarly journals Polarimetric Measurements of Scattered Light by Dust Grains In Earth and Microgravity Conditions. Tentative Interpretation of the Dichotomy between Comets

1996 ◽  
Vol 150 ◽  
pp. 391-394 ◽  
Author(s):  
E. Hadamcik ◽  
A.C. Levasseur-Regourd ◽  
J.C. Worms
Keyword(s):  
Physical Properties ◽  
Phase Angle ◽  
Scattered Light ◽  
Dust Particles ◽  
Laboratory Measurements ◽  
Cometary Dust ◽  
Maximum Value ◽  
Tentative Interpretation ◽  
Microgravity Conditions ◽  
Polarization Of Light

AbstractThe evolution of the polarization of light scattered by dust particles (e.g. cometary dust) with the phase angle is an indicator of the physical properties of the particles. For grains large compared to the wavelength, the maximum value of polarization Pmax increases with increasing size. A dichotomy is pointed out in the cometary poiarimetric phase curves, showing two ranges of values for Pmax. A comparison between laboratory measurements performed under Earth and microgravity conditions is presented. Pmax and the corresponding αmax appear to be smaller in microgravity than for ground based measurements. The comparison between ground based, microgravity and cometary results is then tentatively discussed in term of physical properties of the grains.

scholarly journals Polarimetry of Saturnian satellite Enceladus

2015 ◽  
Vol 5 (1) ◽  
pp. 29-32 ◽  
Author(s):  
S. Zaitsev ◽  
N. Kiselev ◽  
V. Rosenbush ◽  
S. Kolesnikov ◽  
D. Shakhovskoy
Keyword(s):  
Light Scattering ◽  
Phase Angle ◽  
Linear Polarization ◽  
Spectral Band ◽  
Crimean Astrophysical Observatory ◽  
Angle Dependence ◽  
Phase Angles ◽  
Saturnian Satellite

We present results of polarimetric observations of Saturn's moon Enceladus carried out from April 14, 2010 to April 13, 2013 in WR spectral band (550-750 nm). We used 2.6-m telescope equipped with a one-channel photoelectric photometer-polarimeter (Crimean Astrophysical Observatory). The measurements were performed at phase angles ranging from 1.65° to 5.71°. The phase-angle dependence of linear polarization of Enceladus was obtained using the results of our observations. Results obtained are discussed in terms of existing models of light scattering by regolith surfaces.

Physical Properties of Cometary Dust from Light Scattering and Thermal Emission

Comets II ◽  
2004 ◽  
pp. 577-604
Author(s):  
Ludmilla Kolokolova ◽  
Martha S. Hanner ◽  
Anny-Chantal Levasseur-Regourd ◽  
Bo Å. S. Gustafson
Keyword(s):  
Light Scattering ◽  
Physical Properties ◽  
Thermal Emission ◽  
Cometary Dust

scholarly journals Experimental Results on Scattering by Irregular and Meteoritic Dust Particles Related to Photopolarimetry of Zodiacal Light and Comets

1985 ◽  
Vol 85 ◽  
pp. 223-226
Author(s):  
K. Weiss-Wrana ◽  
R.H. Giese ◽  
R.H. Zerull
Keyword(s):  
Light Scattering ◽  
Size Range ◽  
Experimental Results ◽  
Dust Particles ◽  
Dust Grains ◽  
Scattering Function ◽  
Negative Polarization ◽  
Zodiacal Light ◽  
Cometary Dust ◽  
Characteristic Features

AbstractThe investigations of light scattering by larger meteoritic and terrestrial single grains (size range 20 μm to 120 μm ) demonstrate that the scattering properties of irregularly shaped dark opaque particles with very rough surfaces resemble the characteristic features of the empirical scattering function as derived from measurements of the zodiacal light. Purely transparent or translucent irregularly shaped particles show a quite different scattering behaviour. Furthermore irregular and multicomponent fluffy particles in the size range of a few microns were modelled by microwave analog measurements in order to explain positive and negative polarization of the light scattered by cometary dust grains.

scholarly journals Scattering Properties of Cometary Dust Based on Polarimetric Data

1991 ◽  
Vol 126 ◽  
pp. 249-252
Author(s):  
Sonoyo Mukai ◽  
Tadashi Mukai ◽  
Sen Kikuchi
Keyword(s):  
Linear Polarization ◽  
Phase Function ◽  
Mie Scattering ◽  
Mixing Ratio ◽  
Small Particles ◽  
Cometary Dust ◽  
Maximum Polarization ◽  
Large Particles ◽  
Lower Maximum ◽  
Phase Angles

AbstractReferring to the dust model in Mukai and Mukai(1990), where the scattering by large rough particles and Mie scattering by small particles are taken into account, a phase function of linear polarization of several comets is examined, especially in a region of phase angles α near a maximum polarization. A lower maximum polarization observed in comet Austin(1989c1) than those in comets West(1975n) and P/Halley leads a speculation that a mixing ratio of rough scattering to Mie scattering in comet Austin increases from a sun-comet distance r of 0.6 AU to 1.2 AU. This implies that a shortage of large particles in comet Austin occured in r <1 AU.

scholarly journals Scattering Properties of Dust Particles in Weightlessness

1996 ◽  
Vol 150 ◽  
pp. 415-418 ◽  
Author(s):  
J. C. Worms ◽  
A.C. Levasseur-Regourd ◽  
E. Hadamcik ◽  
D. Bourras
Keyword(s):  
Solar System ◽  
Physical Properties ◽  
Dust Particles ◽  
Preliminary Results ◽  
Maximum Polarization ◽  
Microgravity Conditions

AbstractPolarimetric measurements of the light scattered by irregular dust particles are essential to interpret observations of solar system dust in terms of its physical properties. We developed a iight scattering unit to retrieve polarimetric phase curves of dust samples in microgravity conditions. Preliminary results suggest that the values for the maximum polarization are higher under 1 “ g ” than under 0 “ g ” This can be compared to ground-based measurements which exhibit higher values for packed dust than for sifted dust. The unit is operational and is used to help design a related orbital experiment.

scholarly journals Optical and physical properties of aerosols in the boundary layer and free troposphere over the Amazon Basin during the biomass burning season

2006 ◽  
Vol 6 (10) ◽  
pp. 2911-2925 ◽  
Author(s):  
D. Chand ◽  
P. Guyon ◽  
P. Artaxo ◽  
O. Schmid ◽  
G. P. Frank ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Light Scattering ◽  
Physical Properties ◽  
Biomass Burning ◽  
Large Scale ◽  
Amazon Basin ◽  
Single Scattering ◽  
Free Troposphere ◽  
Wet Season ◽  
Average Mass

Abstract. As part of the Large Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) campaign, detailed surface and airborne aerosol measurements were performed over the Amazon Basin during the dry to wet season from 16 September to 14 November 2002. Optical and physical properties of aerosols at the surface, and in the boundary layer (BL) and free troposphere (FT) during the dry season are discussed in this article. Carbon monoxide (CO) is used as a tracer for biomass burning emissions. At the surface, good correlation among the light scattering coefficient (σs at 545 nm), PM2.5, and CO indicates that biomass burning is the main source of aerosols. Accumulation of haze during some of the large-scale biomass burning events led to high PM2.5 (225 μg m−3), σs (1435 Mm−1), aerosol optical depth at 500 nm (3.0), and CO (3000 ppb). A few rainy episodes reduced the PM2.5, number concentration (CN) and CO concentration by two orders of magnitude. The correlation analysis between σs and aerosol optical thickness shows that most of the optically active aerosols are confined to a layer with a scale height of 1617 m during the burning season. This is confirmed by aircraft profiles. The average mass scattering and absorption efficiencies (545 nm) for small particles (diameter Dp<1.5 μm) at surface level are found to be 5.0 and 0.33 m2 g−1, respectively, when relating the aerosol optical properties to PM2.5 aerosols. The observed mean single scattering albedo (ωo at 545 nm) for submicron aerosols at the surface is 0.92±0.02. The light scattering by particles (Δσs/Δ CN) increase 2–10 times from the surface to the FT, most probably due to the combined affects of coagulation and condensation.

scholarly journals Simulation in Laboratory of Solid Grains Present in Space

1991 ◽  
Vol 126 ◽  
pp. 91-94
Author(s):  
L. Colangeli ◽  
E. Bussoletti ◽  
V. Mennella
Keyword(s):  
Mass Spectrometry ◽  
Physical Properties ◽  
Interstellar Dust ◽  
Laboratory Data ◽  
Interplanetary Dust ◽  
Cosmic Dust ◽  
Cometary Dust

AbstractLaboratory data on cosmic dust analogue materials are compared with recent results obtained by means of spectroscopy and mass spectrometry on cometary dust, meteorites and interplanetary dust. Their actual chemical and physical properties can be further clarified, as well as possible links with interstellar dust.

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