Photometric Studies of Asteroids. V. The Light-Curve and Phase Function of 20 Massalia.

Gehrels, T.

doi:10.1086/146166

Cited by 96 publications

(48 citation statements)

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“…The sharp polarization surge for Saturn's rings can be called the polarization opposition effect (Mishchenko 1993). Gehrels (1956) confirmed the nonlinear opposition brightening (magnitude scale) for the asteroid (20) Massalia, and introduced the term "opposition effect". The lunar opposition effect was then pointed out by Gehrels et al (1964) and by van Diggelen (1964), although it was already discovered by Barabashev (1922) and Markov (1924), and could be distinguished in Rougier's extensive observations (1933).…”

Section: Observationsmentioning

confidence: 89%

Coherent Backscattering by Solar System Dust Particles

Muinonen¹

1994

Symp. - Int. Astron. Union

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Abstract. I review progress in interpreting the opposition effect and negative linear polarization observed for solar system dust particles. The so-called coherent backscattering mechanism has recently been introduced to explain the observations. However, fundamental difficulties in theoretical modeling still prevent quantitative interpretation. I also review some of the key observations that questioned the hitherto widely accepted mutual-shadowing explanation for the opposition effect. I summarize previous theoretical and experimental work on the opposition effect and negative polarization.

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Section: Observationsmentioning

confidence: 89%

Coherent Backscattering by Solar System Dust Particles

Muinonen¹

1994

Symp. - Int. Astron. Union

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“…Pospieszalska-Surdej & Surdej 1985;Magnusson 1986) take advantage of this direct dependence. However, the discovery by Gehrels (1956), that the lightcurve amplitude of Asteroid 20 Massalia increases with phase angle (a behavior that subsequently has been observed for many other asteroids), is a more delicate problem, which lacks a simple explanation.…”

Section: Previous Workmentioning

confidence: 99%

Comments on the amplitude-phase relationship of asteroid lightcurves

Gutiérrez¹,

Davidsson

Ortiz³

et al. 2006

A&A

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Aims. We present a theoretical study on the amplitude-phase relationship (APR) for lightcurves of simulated asteroids. Methods. In support of the Rosetta (ESA) mission, we developed a numerical model for the investigation of the light reflectance properties of asteroidal bodies. The code is able to deal with irregular and chemically inhomogeneous surfaces, taking shadowing effects into account. Several standard scattering models have been implemented, which govern local reflectance properties, e.g. the Hapke model and the Lumme-Bowell model. From a kinematic standpoint, the body can move in an arbitrary orbit, and it may rotate in either pure or complex mode with an arbitrary orientation of its angular momentum. As an application of the code, we studied the dependence of the APR on several factors, such as the illumination and observational geometries, overall shape, and large-scale topography, as well as the surface characteristics represented by the parameters in the Hapke and Lumme-Bowell models. Results. In our study, we find that mineralogy, regolith properties, and small-scale surface roughness (i.e., characteristics embodied in the considered surface scattering models), have a negligible effect on the APR. Furthermore, large-scale topography introduces a rather significant dispersion in the APR slope, on the order of 0.010 mag deg −1 . Our simulations suggest that obliquity is the major agent for shaping the APR, causing a 0.020 mag deg −1 dispersion in the APR slope; the larger the obliquity, the smaller the slope of the APR. For intermediate aspect angles, large obliquities could even lead to an amplitude that decreases with the phase angle.

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“…The sharp increase in asteroid brightness near opposition has been known for a long time (Gehrels 1956). At first the opposition effect (OE) was considered to be very similar among different types of asteroids (Gehrels andTaylor 1977, Gehrels andTedesco 1979).…”

Section: Introductionmentioning

confidence: 96%