Gravitational slopes, geomorphology, and material strengths of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Groussin, O.; Jordá, L.; Auger, A.-T.; Kührt, Ekkehard; Gaskell, R. W.; Capanna, Claire; Scholten, F.; Preusker, Frank; Lamy, Philippe; Hviid, S. F.; Knollenberg, J.; Keller, U.; Huettig, C.; Sierks, H.; Barbieri, C.; Rodrigo, R.; Koschny, D.; Rickman, H.; A’Hearn, Michael F.; Agarwal, Jessica; Barucci, M. A.; Bertaux, Jean-Loup; Bertini, Ivano; Boudreault, S.; Cremonese, G.; Deppo, Vania Da; Davidsson, B.; Debei, S.; Cecco, M. De; El‐Maarry, M. R.; Fornasier, S.; Fulle, M.; Gutiérrez, P. J.; Güttler, C.; Ip, W. H.; Kramm, J.-R.; Küppers, M.; Lazzarin, M.; Lara, L. M.; Moreno, J. J. Lopez; Marchi, S.; Marzari, F.; Massironi, Matteo; Michalik, H.; Naletto, G.; Oklay, N.; Pommerol, Antoine; Pajola, M.; Thomas, N.; Tóth, I.; Tubiana, C.; Vincent, Jean‐Baptiste

doi:10.1051/0004-6361/201526379

Cited by 121 publications

(69 citation statements)

References 53 publications

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“…After one orbit, they observed the retreat of a scarp with downward erosion of > 20m, and morphological changes of depressions in smooth terrains. Similar large scale changes were observed on comet 67P (Groussin, 2015). In addition, Rosetta also discovered many other types of changes, like fault extension, cliff collapse, transport of large boulders, summarized in El-Maarry et al (2017) and Chapter "Morphology" of this book.…”

Section: Morphological Changessupporting

confidence: 54%

Local Manifestations of Cometary Activity

et al. 2019

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Comets are made of volatile and refractory material and naturally experience various degrees of sublimation as they orbit around the Sun. This gas release, accompanied by dust, represents what is traditionally described as activity. Although the basic principles are well established, most details remain elusive, especially regarding the mechanisms by which dust is detached from the surface and subsequently accelerated by the gas flows surrounding the nucleus.During its 2 years rendez-vous with comet 67P/Churyumov-Gerasimenko, ESA's Rosetta has observed cometary activity with unprecedented details, in both the inbound and outbound legs of the comet's orbit. This trove of data provides a solid ground on which new models of activity can be built. In this chapter, we review how activity manifests at close distance from the surface, establish a nomenclature for the different types of observed features, discuss how activity is at the same time transforming and being shaped by the topography, and finally address several potential mechanisms.

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Section: Morphological Changessupporting

confidence: 54%

Local Manifestations of Cometary Activity

et al. 2019

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“…In addition to three dust analyzers, OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) also provide images of the nucleus as well as dust particles. Based on the OSIRIS images, the tensile strength of comet 67P is estimated (Groussin et al 2015;Basilevsky et al 2016). Recently, Tatsuuma et al (2019) studied the tensile strength of dust aggregates and found that the tensile strength of comet 67P is reproduced when the monomer radius is between 3.3 − 220 µm.…”

Section: Comparison With Cometary Dust In the Solar Systemmentioning

confidence: 99%

Unveiling Dust Aggregate Structure in Protoplanetary Disks by Millimeter-wave Scattering Polarization

Tazaki

Tanaka

Kataoka

et al. 2019

ApJ

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Dust coagulation in a protoplanetary disk is the first step of planetesimal formation. However, the pathway from dust aggregates to planetesimals remains unclear. Both numerical simulations and laboratory experiments have suggested the importance of dust structure in planetesimal formation, but it is not well constrained by observations. We study how the dust structure and porosity alters polarimetric images at millimeter wavelength by performing 3D radiative transfer simulations. Aggregates with different porosity and fractal dimension are considered. As a result, we find that dust aggregates with lower porosity and/or higher fractal dimension are favorable to explain the observed millimeter-wave scattering polarization of disks. Although we cannot rule out the presence of aggregates with extremely high porosity, a population of dust particles with relatively compact structure is at least necessary to explain polarized-scattered waves. In addition, we show that particles with moderate porosity show weak wavelength dependence of scattering polarization, indicating that multi-wavelength polarimetry is useful to constrain dust porosity. Finally, we discuss implications for dust evolution and planetesimal formation in disks.

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“…There are many unexpected results about 67P (e.g., Fulle et al 2016), and especially it is remarkable that its tensile strength arXiv:1902.08356v1 [astro-ph.EP] 22 Feb 2019 was estimated. The tensile strength of 67P for its surface is 3-150 Pa (Groussin et al 2015;Basilevsky et al 2016), while for bulk comet 10-200 Pa (Hirabayashi et al 2016). This tensile strength depends on composition and formation process of comets, i.e., planetesimals.…”

Section: Introductionmentioning

confidence: 99%

Tensile Strength of Porous Dust Aggregates

Tatsuuma

Kataoka

Tanaka

2019

ApJ

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Comets are thought to have information about the formation process of our solar system. Recently, detailed information about comet 67P/Churyumov-Gerasimenko has been found by a spacecraft mission Rosetta. It is remarkable that its tensile strength was estimated. In this paper, we measure and formulate the tensile strength of porous dust aggregates using numerical simulations, motivated by porous dust aggregation model of planetesimal formation. We perform three-dimensional numerical simulations using a monomer interaction model with periodic boundary condition. We stretch out a dust aggregate with a various initial volume filling factor between 10 −2 and 0.5. We find that the tensile stress takes the maximum value at the time when the volume filling factor decreases to about a half of the initial value. The maximum stress is defined to be the tensile strength. We take an average of the results with 10 different initial shapes to smooth out the effects of initial shapes of aggregates. Finally, we numerically obtain the relation between the tensile strength and the initial volume filling factor of dust aggregates. We also use a simple semi-analytical model and successfully reproduce the numerical results, which enables us to apply to a wide parameter range and different materials. The obtained relation is consistent with previous experiments and numerical simulations about silicate dust aggregates. We estimate that the monomer radius of comet 67P has to be about 3.3-220 µm to reproduce its tensile strength using our model.

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Gravitational slopes, geomorphology, and material strengths of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Cited by 121 publications

References 53 publications

Local Manifestations of Cometary Activity

Local Manifestations of Cometary Activity

Unveiling Dust Aggregate Structure in Protoplanetary Disks by Millimeter-wave Scattering Polarization

Tensile Strength of Porous Dust Aggregates

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