Cometary topography and phase darkening. (arXiv:1901.06250v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Vincent_J/0/1/0/all/0/1">Jean-Baptiste Vincent</a>
Cometary surfaces can change significantly and rapidly due to the sublimation
of their volatile material. Many authors have investigated this evolution;
Vincent et al. (2017) have used topographic data from all comets visited by
spacecrafts to derive a quantitative model which relates large scale roughness
(i.e. topography) with the evolution state of the nucleus for Jupiter Family
Comets (JFCs). Meanwhile, ground based observers have published measurements of
the phase functions of many JFCs and reported a trend in the phase darkening,
with primitive objects showing a stronger darkening than evolved ones).
In this paper, we use a numerical implementation of the topographic
description by Vincent et al. (2017) to build virtual comets and measure the
phase darkening induced by the different levels of macro-roughness. We then
compare our model with the values published by Kokotanekova et al. (2018)
We find that pure geometric effects like self-shadowing can represent up to
22% of the darkening observed for more primitive objects, and 15% for evolved
surfaces. This shows that although physical and chemical properties remain the
major contributor to the phase darkening, the additional effect of the
topography cannot be neglected.
Cometary surfaces can change significantly and rapidly due to the sublimation
of their volatile material. Many authors have investigated this evolution;
Vincent et al. (2017) have used topographic data from all comets visited by
spacecrafts to derive a quantitative model which relates large scale roughness
(i.e. topography) with the evolution state of the nucleus for Jupiter Family
Comets (JFCs). Meanwhile, ground based observers have published measurements of
the phase functions of many JFCs and reported a trend in the phase darkening,
with primitive objects showing a stronger darkening than evolved ones).
In this paper, we use a numerical implementation of the topographic
description by Vincent et al. (2017) to build virtual comets and measure the
phase darkening induced by the different levels of macro-roughness. We then
compare our model with the values published by Kokotanekova et al. (2018)
We find that pure geometric effects like self-shadowing can represent up to
22% of the darkening observed for more primitive objects, and 15% for evolved
surfaces. This shows that although physical and chemical properties remain the
major contributor to the phase darkening, the additional effect of the
topography cannot be neglected.
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