Application of the multiple sphere superposition solution to large–scale systems of spheres via an accelerated algorithm

Mackowski, Daniel W.; Kolokolova, L.

doi:10.1016/j.jqsrt.2022.108221

Cited by 10 publications

(2 citation statements)

References 32 publications

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“…Light scattered by this type of smaller particle is expected to be more polarized than that scattered by larger particles. Furthermore, an increased amount of ice in the particles ejected from the subsurface layers may increase polarization, as shown by the comparison between the polarization from icy particles and that from silicates or organics made by Mackowski & Kolokolova (2022).…”

Section: Discussionmentioning

confidence: 99%

Optical Spectropolarimetry of Binary Asteroid Didymos–Dimorphos before and after the DART Impact

Bagnulo

Gray

Granvik

et al. 2023

ApJL

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We have monitored the Didymos–Dimorphos binary asteroid in spectropolarimetric mode in the optical range before and after the DART impact. The ultimate goal was to obtain constraints on the characteristics of the ejected dust for modeling purposes. Before impact, Didymos exhibited a linear polarization rapidly increasing with phase angle, reaching a level of ∼5% in the blue and ∼4.5% in the red. The shape of the polarization spectrum was anticorrelated with that of its reflectance spectrum, which appeared typical of an S-class asteroid. After impact, the level of polarization dropped by about 1 percentage point (pp) in the blue band and about 0.5 pp in the red band, then continued to linearly increase with phase angle, with a slope similar to that measured prior to impact. The polarization spectra, once normalized by their values at an arbitrary wavelength, show very little or no change over the course of all observations before and after impact. The lack of any remarkable change in the shape of the polarization spectrum after impact suggests that the way in which polarization varies with wavelength depends on the composition of the scattering material, rather than on its structure, be this a surface or a debris cloud.

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Section: Discussionmentioning

confidence: 99%

Optical Spectropolarimetry of Binary Asteroid Didymos–Dimorphos before and after the DART Impact

Bagnulo

Gray

Granvik

et al. 2023

ApJL

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“…We expect P r to be independent of the size for larger aggregate scales of interest in typical Halley-dust composition(Mackowski & Kolokolova 2022). This makes us consider a simple dust cluster of monodisperse monomers.…”

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confidence: 99%

Examining the dust of the tailless Oort-cloud comet C/2020 T2

Kwon

Masiero

Markkanen

2022

A&A

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We report our new analysis of Oort-cloud comet C/2020 T2 (Palomar) (T2) observed at 2.06 au from the Sun (phase angle of 28. • 5) about two weeks before perihelion. T2 lacks a significant dust tail in scattered light, showing a strong central condensation of the coma throughout the apparition, reminiscent of so-called Manx comets. Its spectral slope of polarized light increases and decreases in the J (1.25 µm) and H (1.65 µm) bands, respectively, resulting in an overall negative (blue) slope (−0.31±0.14 % µm −1 ) in contrast to the red polarimetric color of active comets observed at similar geometries. The average polarization degree of T2 is 2.86±0.17 % for the J and 2.75±0.16 % for the H bands. Given that near-infrared wavelengths are sensitive to the intermediate-scale structure of cometary dust (i.e., dust aggregates), our light-scattering modeling of ballistic aggregates with different porosities and compositions shows that polarimetric properties of T2 are compatible with low-porosity (∼66 %), absorbing dust aggregates with negligible ice contents on a scale of 10-100 µm (density of ∼652 kg m −3 ). This is supported by the coma morphology of T2 which has a viable β (the relative importance of solar radiation pressure on dust particles) range of 10 −4 . Secular evolution of r-band activity of T2 from archival data reveals that the increase in its brightness accelerates around 2.4 au pre-perihelion, with its overall dust production rate 100 times smaller than those of active Oort-cloud comets. We also found an apparent concentration of T2 and Manx comets toward ecliptic orbits. This paper underlines the heterogeneous nature of Oort-cloud comets which can be investigated in the near future with dedicated studies of their dust characteristics.

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Improvement of the Mean Field T-Matrix method for scattering by fractal aggregates of identical spheres in astrophysical environments

Rannou,

Botet,

Tazaki

2024

Icarus

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Application of the multiple sphere superposition solution to large–scale systems of spheres via an accelerated algorithm

Cited by 10 publications

References 32 publications

Optical Spectropolarimetry of Binary Asteroid Didymos–Dimorphos before and after the DART Impact

Optical Spectropolarimetry of Binary Asteroid Didymos–Dimorphos before and after the DART Impact

Examining the dust of the tailless Oort-cloud comet C/2020 T2

Improvement of the Mean Field T-Matrix method for scattering by fractal aggregates of identical spheres in astrophysical environments

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