J/A+A/624/A5 Cometary topography and phase darkening (Vincent, 2019)
Cometary topography and phase darkening.
Vincent J.-B.
<Astron. Astrophys. 624, A5 (2019)>
=2019A&A...624A...5V 2019A&A...624A...5V (SIMBAD/NED BibCode)
ADC_Keywords: Comets ; Models
Keywords: comets: general
Abstract:
Cometary surfaces can change significantly and rapidly due to the
sublimation of their volatile material. Many authors have investigated
this evolution; Vincent et al. (2017MNRAS.469S.329V 2017MNRAS.469S.329V) 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. (2017MNRAS.469S.329V 2017MNRAS.469S.329V) 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. (2018MNRAS.479.4665K 2018MNRAS.479.4665K)
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.
Description:
The associated file "comet_topo.blend" contains the python code and
software environment used to generate virtual comets in the paper.
The code relies on the internal Python environment provided by Blender
(free and open-source 3D modeling software available at
www.blender.org). To avoid path issues, the code is embedded into the
into the .blend file and must be run from within Blender.
Upon opening, "comet_topo.blend" with Blender 2.8, you will be
presented with all relevant instructions to run, modify, or export the
code.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
comet_topo.blend 512 1327 Python code and software environment
--------------------------------------------------------------------------------
Acknowledgements:
Jean-Baptiste Vincent, Jean-Baptiste.Vincent(at)dlr.de
(End) Patricia Vannier [CDS] 28-Jan-2019