A Model of Spectral Albedo of Particulate Surfaces: Implications for Optical Properties of the Moon

Shkuratov, Yurij G.; Starukhina, L. V.; Hoffmann, H.; Arnold, Gabriele

doi:10.1006/icar.1998.6035

Cited by 403 publications

(340 citation statements)

References 27 publications

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“…Although the derived silicate compositions of 241662 (2000 KO44) and19764 (2000 NF5) are consistent with that of LL ordinary chondrites, we noticed that their olivine abundances (66%) are lower than the ranges found by Vernazza et al (2008) for LL chondrites (70-85%), and members of the Flora family (76-82%). However, this discrepancy could be explained by the fact that Vernazza et al (2008) used a radiative transfer model (Shkuratov et al, 1999) to calculate the ol/(ol + px) ratios, while we used empirical spectral calibrations derived from the analysis of ordinary chondrites.…”

Section: Discussionmentioning

confidence: 99%

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Sanchez

Michelsen

Reddy

et al. 2013

Icarus

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In the past, constraining the surface composition of near-Earth asteroids (NEAs) has been difficult due to the lack of high quality near-IR spectral data (0.7-2.5 µm) that contain mineralogically diagnostic absorption bands. Here we present visible (∼ 0.43-0.95 µm) and nearinfrared (∼ 0.7-2.5 µm) spectra of nine NEAs and five Mars-crossing asteroids (MCs). The YT1) as a V-type was made on the basis of its near-infrared spectrum since no visible spectrum is available for this asteroid. A mineralogical analysis was performed on six of the asteroids (those for which near-IR spectra were obtained or previously available). We found that three asteroids (241662 (2000 KO44), 19764 (2000 NF5), 138404 (2000) have mafic silicate compositions consistent with ordinary chondrites, while three others (4055 Magellan, 164121 (2003 YT1), 5407 (1992 AX)) are pyroxene-dominated basaltic achondrite assemblages. In the case of 5407 (1992 AX) we found that its basaltic surface composition contrasts its taxonomic classification as a S-type.

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Section: Discussionmentioning

confidence: 99%

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Sanchez

Michelsen

Reddy

et al. 2013

Icarus

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“…We used the Shkuratov theory (Shkuratov et al 1999) to generate a collection of synthetic spectra that reproduce the overall shape of the spectrum of the whole system, which includes Chariklo and rings. These models use the optical constants as input, the relative abundance and the size of the particles of different materials to compute the geometric albedo of the surface at different wavelengths.…”

Section: Spectral Modelingmentioning

confidence: 99%

Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo

Duffárd

Pinilla-Alonso

Ortiz

et al. 2014

A&A

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Context. A stellar occultation observed on 3rd June 2013 revealed the presence of two dense and narrow rings separated by a small gap around the Centaur object (10 199) Chariklo. The composition of these rings is not known. We suspect that water ice is present in the rings, as is the case for Saturn and other rings around the giant planets. Aims. In this work, we aim to determine if the variability in the absolute magnitude of Chariklo and the temporal variation of the spectral ice feature, even when it disappeared in 2007, can be explained by an icy ring system whose aspect angle changes with time. Methods. We explained the variations on the absolute magnitude of Chariklo and its ring by modeling the light reflected by a system as the one described above. Using X-shooter at VLT, we obtained a new reflectance spectra. We compared this new set of data with the ones available in the literature. We showed how the water ice feature is visible in 2013 in accordance with the ring configuration, which had an opening angle of nearly 34 • in 2013. Finally, we also used models of light scattering to fit the visible and near-infrared spectra that shows different characteristics to obtain information on the composition of Chariklo and its rings. Results. We showed that absolute photometry of Chariklo from the literature and new photometric data that we obtained in 2013 can be explained by a ring of particles whose opening angle changes as a function of time. We used the two possible pole solutions for the ring system and found that only one of them, α = 151.30 ± 0.5, δ = 41.48 ± 0.2 • (λ = 137.9 ± 0.5, β = 27.7 ± 0.2 • ), provides the right variation of the aspect angle with time to explain the photometry, whereas the other possible pole solution fails to explain the photometry. From spectral modeling, we derived the composition of the Chariklo surface and that of the rings using the result on the pole solution. Chariklo surface is composed with about 60% of amorphous carbon, 30% of silicates and 10% of organics; no water ice was found on the surface. The ring, on the other hand, contains 20% of water ice, 40−70% of silicates, and 10−30% of tholins and small quantities of amorphous carbon.

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“…Molecular mixtures consist of inclusions in a medium (usually ice) of contaminant particles. In this case, optical constants for the contaminated material are calculated by means of the effective medium theory (Shkuratov 1999). Intimate mixtures are the common salt and pepper mixtures.…”

Section: Adopted Codementioning

confidence: 99%

Composition of KBO (50000) Quaoar

Ore

Barucci

Emery³

et al. 2009

A&A

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Aims. The objective of this work is to investigate the physical properties of objects beyond Neptune -the new frontiers of the Solar System -and in particular to study the surface composition of (50 000) Quaoar, a classical Transneptunian (or Kuiper Belt) object. Because of its distance from the Sun, Quaoar is expected to have preserved, to a degree, its original composition. Our goals are to determine to what degree this is true and to shed light on the chemical evolution of this icy body. Methods. We present new near-infrared (3.6 and 4.5 μm) photometric data obtained with the Spitzer Space Telescope. These data complement high resolution, low signal-to-noise spectroscopic and photometric data obtained in the visible and near-infrared (0.4-2.3 μm) at VLT-ESO and provide an excellent set of constraints in the model calculation process. We perform spectral modeling of the entire wavelength range -from 0.3 to 4.5 μm by means of a code based on the Shkuratov radiative transfer formulation of the slab model. We also attempt to determine the temperature of H 2 O ice making use of the crystalline feature at 1.65 μm.Results. We present a model confirming previous results regarding the presence of crystalline H 2 O and CH 4 ice, as well as C 2 H 6 and organic materials, on the surface of this distant icy body. We attempt a measurement of the temperature and find that stronger constraints on the composition are needed to obtain a precise determination. Conclusions. Model fits indicate that N 2 may be a significant component, along with a component that is bright at λ > 3.3 μm, which we suggest at this time could be amorphous H 2 O ice in tiny grains or thin grain coatings. Irradiated crystalline H 2 O could be the source of small-grained amorphous H 2 O ice. The albedo and composition of Quaoar, in particular the presence of N 2 , if confirmed, make this TNO quite similar to Triton and Pluto.

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A Model of Spectral Albedo of Particulate Surfaces: Implications for Optical Properties of the Moon

Cited by 403 publications

References 27 publications

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids

Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo

Composition of KBO (50000) Quaoar

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