Planetary surface texture and albedo from parameter plots of optical polarization data

Geake, J. E.; Dollfus, Audouin

doi:10.1093/mnras/218.1.75

Cited by 69 publications

(68 citation statements)

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“…This group was separated on the basis of the measurements of lunar fines with average grain sizes of the order of 10 μm across a range from smaller than 1 μm to several tens of microns (e.g., Geake & Dollfus 1986). Lutetia's data were later interpreted as being indicative of a metallic surface with a grain size of 20-40 μm (Dollfus et al 1979).…”

Section: Polarimetrymentioning

confidence: 99%

“…The arrow shows the changes in the inversion angle for the CV3 chondrite Allende when these angles are measured for either a solid piece or a crushed sample. Data for meteorites are taken from Zellner et al (1977), Geake & Dollfus (1986), Shkuratov et al (1984), Lupishko & Belskaya (1989). Asteroid polarimetric parameters were calculated by fitting a linear-exponentional function to the data for individual asteroids in the Asteroid Polarimetric Database.…”

Section: Polarimetrymentioning

confidence: 99%

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Puzzling asteroid 21 Lutetia: our knowledge prior to the Rosetta fly-by

Belskaya

Fornasier

Krugly

et al. 2010

A&A

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Aims. A wide observational campaign was carried out in [2004][2005][2006][2007][2008][2009] that aimed to complete the ground-based investigation of Lutetia prior to the Rosetta fly-by in July 2010. Methods. We obtained BVRI photometric and V-band polarimetric measurements over a wide range of phase angles, and visible and infrared spectra in the 0.4-2.4 μm range. We analyze them with previously published data to retrieve information about Lutetia's surface properties.Results. Values of lightcurve amplitudes, absolute magnitude, opposition effect, phase coefficient, and BVRI colors of Lutetia surface seen at near pole-on aspect are determined. We define more precisely parameters of polarization phase curve and show their distinct deviation from any other moderate-albedo asteroid. An indication of possible variations in both polarization and spectral data across the asteroid surface are found. To explain features found by different techniques, we propose that (i) Lutetia has a non-convex shape, probably due to a large crater, and heterogeneous surface properties probably related to surface morphology; (ii) at least part of the surface is covered by a fine-grained regolith of particle size smaller than 20 μm; (iii) the closest meteorite analogues of Lutetia's surface composition are particular types of carbonaceous chondrites, or Lutetia has specific surface composition that is not representative among studied meteorites.

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Section: Polarimetrymentioning

confidence: 99%

Section: Polarimetrymentioning

confidence: 99%

Puzzling asteroid 21 Lutetia: our knowledge prior to the Rosetta fly-by

Belskaya

Fornasier

Krugly

et al. 2010

A&A

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“…), the maximal phase angle that can be achieved with ground-based observations is approximately 48º, which does not allow for its positive polarization maximum to be measured from Earth. Such a limitation inspired the search for analogs of the Umov effect at smaller α (e.g., Geake and Dollfus, 1986;Wolff, 1980). For asteroids and planetary satellites, instead of using the Umov effect, reliable estimates of geometric albedo can be carried out using the inverse correlation log(h) -log(A), where h is the slope of the polarization curve at the inversion angle (e.g., Cellino et al, 1999;Geake and Dollfus, 1986;Lupishko and Mohamed, 1996;Shkuratov, 1980;Wolff, 1980;Zellner et al, 1977a,b).…”

Section: The Log(h) -Log(a) Diagrammentioning

confidence: 99%

“…One interesting consequence of the Umov effect is to link the slope h of the polarization curve at the inversion phase angle α inv to the geometric albedo A (e.g., Zellner et al, 1977a,b;Geake and Dollfus, 1986;Wolff, 1980;Shkuratov 1980;. The correlation between h and A is widely used to determine albedo of asteroids (e.g., Lupishko and Mohamed, 1996;Cellino et al, 1999;.…”

Section: Introductionmentioning

confidence: 99%

The Umov effect for single irregularly shaped particles with sizes comparable with wavelength

Zubko

Videen

Shkuratov³

et al. 2011

Icarus

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Abstract. The Umov effect manifests itself as an inverse correlation between the linear polarization maximum of an object's scattered light P max and its geometric albedo A. This effect is observed for the Moon, Mercury and Mars, and there are data suggesting this effect is valid for asteroids. The Umov effect is due to the contribution of interparticle multiple scattering that increases albedo and decreases polarization. We here study if the Umov effect can be extended to the case of single irregularly shaped particles with sizes comparable with the wavelength. This, in particular, is important for cometary dust polarimetry. We show the Umov effect being valid for weakly absorbing irregular particles (Im(m) ≤ 0.02) almost through the entire range of size parameters x considered. Highly absorbing particles (Im(m)>0.02) follow the Umov effect only if x exceeds 14. In the case of weakly absorbing particles, the inverse correlation is essentially non-linear, which is caused by the contribution of particles with small x. However, averaging over many different types of irregularly shaped particles could make it significantly more linear.The size averaging does not change qualitatively the diagram log(P max ) -log(A) for weakly absorbing particles. For single irregular particles whose sizes are comparable with wavelength, there is no reliable correlation between the slope of the polarization curve h near the inversion phase angle and geometrical albedo A. Using the extended Umov law, we estimate the geometric albedo of dust particles forming cometary circumnuclear haloes A = 0.1 -0.2, which is a few times larger than the average geometric albedo over the entire comae. Note that, using the obtained values for A of cometary particles, one can derive their number density in circumnuclear haloes from photometric observations.

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“…• beyond the inversion point β co (see Geake and Dollfus 1986). More recently, another technique was developed and uses a polynomial or trigonometric fit to represent all data between phase angles 0…”

Section: Polarization As a Function Of The Phase Angle βmentioning

confidence: 99%