Dynamics and potential origins of decimeter-sized particles around comet 67P/Churyumov-Gerasimenko

Abstract

Methods. We algorithmically tracked thousands of individual particles through four OSIRIS/NAC image sequences of 67P's near-nucleus coma. We then traced concentrated particle groups back to the nucleus surface, and estimated their potential source regions, size distributions, and projected dynamical parameters. Finally, we compared the observed activity to dust coma simulations. Results. We traced back 409 decimeter-sized particles to four suspected source regions. The regions strongly overlap and are mostly confined to the Khonsu-Atum-Anubis area. The activity may be linked to rugged terrain, and the erosion of fine dust and the ejection of large boulders may be mutually exclusive. Power-law indices fitted to the particle size--frequency distributions range from $3.4\pm 0.3$ to $3.8\pm 0.4$. Gas drag fits to the radial particle accelerations provide an estimate for the local gas production rates ($Q_{\text{g}}=3.6\cdot 10^{-5}$ kg s${}^{-1}$ m${}^{-2}$), which is several times higher than our model predictions based on purely insolation-driven water ice sublimation. Our observational results and our modeling results both reveal that our particles were likely ejected with substantial nonzero initial velocities of around 0.5$-$0.6 m s${}^{-1}$. Conclusions. Our findings strongly suggest that the observed ejection of decimeter-sized particles cannot be explained by water ice sublimation and favorable illumination conditions alone. Instead, the local structures and compositions of the source regions likely play a major role. In line with current ejection models of decimeter-sized particles, we deem an overabundance of CO${}_2$ ice and its sublimation to be the most probable driver. In addition, because of the significant initial velocities, we suspect the ejection events to be considerably more energetic than gradual liftoffs.

arXiv comment31 pages, 29 figures

References in corpus (47)

• Power-law distributions in empirical data
• Powerlaw: a Python package for analysis of heavy-tailed distributions
• Power-law distributions in binned empirical data
• Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles
• Synthesis of the Morphological Description of Cometary Dust at Comet 67P
• Summer fireworks on comet 67P
• Gravitational slopes, geomorphology, and material strengths of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations
• Seasonal Mass Transfer on the Nucleus of Comet 67P/Chuyumov-Gerasimenko
• A Distribution of Large Particles in the Coma of Comet 103P/Hartley 2
• Are fractured cliffs the source of cometary dust jets ? Insights from OSIRIS/Rosetta at 67P
• The Rosetta mission orbiter Science overview the comet phase
• The size distribution of Jupiter Family comet nuclei
• What drives the dust activity of comet 67P/Churyumov-Gerasimenko?
• The Surface Distributions of the Production of the Major Volatile Species, H2O, CO2, CO and O2, from the Nucleus of Comet 67P/Churyumov-Gerasimenko throughout the Rosetta Mission as Measured by the ROSINA Double Focusing Mass Spectrometer
• The gas production of 14 species from comet 67P/Churyumov-Gerasimenko based on DFMS/COPS data from 2014-2016
• The Dust Trail of Comet 67P/Churyumov-Gerasimenko between 2004 and 2006
• Cometary Dust Trail Associated with Rosetta Mission Target: 67P/Churyumov-Gerasimenko
• Acceleration of Individual, Decimetre-sized Aggregates in the Lower Coma of Comet 67P/Churyumov-Gerasimenko
• Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 3
• Tensile Strength of 67P/Churyumov-Gerasimenko Nucleus Material from Overhangs
• The Dust Trail of Comet 67P/Churyumov-Gerasimenko
• Spitzer Observations of Comet 67P/Churyumov-Gerasimenko at 5.5-4.3 AU From the Sun
• Interpretation of the phase functions measured by the OSIRIS instrument for Comet 67P/Churyumov-Gerasimenko
• The highly active Anhur-Bes regions in the 67P/Churyumov - Gerasimenko comet: results from OSIRIS/ROSETTA observations
• Airfall on Comet 67P/Churyumov-Gerasimenko
• Acceleration of cometary dust near the nucleus: Application to 67P/Churyumov-Gerasimenko
• Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko
• Formation of Comets
• Thermal fracturing on comets. Applications to 67P/Churyumov-Gerasimenko
• Dynamics and distribution of Jovian dust ejected from the Galilean satellites
• On the origin of inner coma structures observed by Rosetta during a diurnal rotation of comet 67P/Churyumov-Gerasimenko
• Prevailing dust-transport directions on comet 67P/Churyumov-Gerasimenko
• Volatile exposures on the 67P/Churyumov-Gerasimenko nucleus
• Experiments on cometary activity: ejection of dust aggregates from a sublimating water-ice surface
• A quantitative description of comet 67P's dust and gas production remains enigmatic
• Cometary surface dust layers built out of millimetre-scale aggregates: dependence of modelled cometary gas production on the layer transport properties
• Coma environment of comet C/2017 K2 around the water ice sublimation boundary observed with VLT/MUSE
• Limitations in the determination of surface emission distributions on comets through modelling of observational data -- A case study based on Rosetta observations
• CO2-driven surface changes in the Hapi region on Comet 67P/Churyumov-Gerasimenko
• Dynamics of irregularly-shaped cometary particles subjected to outflowing gas and solar radiative forces and torques
• Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov-Gerasimenko
• The ice composition close to the surface of comet 67P/Churyumov-Gerasimenko
• Diurnal ejection of boulder clusters on comet 67P lasting beyond 3 AU
• Thermophysical model for icy cometary dust particles
• Motion of Dust Ejected from the Surface of Asteroid (101955) Bennu
• Distribution and dynamics of decimeter-sized dust agglomerates in the coma of 67P/Churyumov-Gerasimenko
• On the trail of a comet's tail: A particle tracking algorithm for comet 67P/Churyumov-Gerasimenko

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