The Nucleus of comet 67P/Churyumov–Gerasimenko – Part I: The global view – nucleus mass, mass-loss, porosity, and implications

Pätzold, M.; Andert, T.; Hahn, M.; Barriot, Jean‐Pierre; Asmar, S. W.; Häusler, B.; Bird, M. K.; Tellmann, S.; Oschlisniok, Janusz; Peter, Kerstin

doi:10.1093/mnras/sty3171

Cited by 107 publications

(85 citation statements)

References 29 publications

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“…3), the mass loss rate in chunks is larger for 103P (Fulle et al 2019), thereby explaining its hyperactivity. Estimates of the refractory-to-ice mass ratio in 67P (Herique et al 2016;Pätzold et al 2019;Fulle et al 2019) converge to values between δ = 3 and 7, matching the rough estimate of δ = 3 for 103P (Fulle et al 2019).…”

Section: Correlation Between the D/h Ratio And Hyperactivitysupporting

confidence: 67%

Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets

Lis

Bockelée‐Morvan

Güsten

et al. 2019

A&A

108

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The D/H ratio in cometary water has been shown to vary between 1 and 3 times the Earth's oceans value, in both Oort cloud comets and Jupiter-family comets originating from the Kuiper belt. This has been taken as evidence that comets contributed a relatively small fraction of the terrestrial water. We present new sensitive spectroscopic observations of water isotopologues in the Jupiterfamily comet 46P/Wirtanen carried out using the GREAT spectrometer aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The derived D/H ratio of (1.61 ± 0.65) × 10 −4 is the same as in the Earth's oceans. Although the statistics are limited, we show that interesting trends are already becoming apparent in the existing data. A clear anti-correlation is seen between the D/H ratio and the active fraction, defined as the ratio of the active surface area to the total nucleus surface. Comets with an active fraction above 0.5 typically have D/H ratios in water consistent with the terrestrial value. These hyperactive comets, such as 46P/Wirtanen, require an additional source of water vapor in their coma, explained by the presence of subliming icy grains expelled from the nucleus. The observed correlation may suggest that hyperactive comets belong to a population of ice-rich objects that formed just outside the snow line, or in the outermost regions of the solar nebula, from water thermally reprocessed in the inner disk that was transported outward during the early disk evolution. The observed anti-correlation between the active fraction and the nucleus size seems to argue against the first interpretation, as planetesimals near the snow line are expected to undergo rapid growth. Alternatively, isotopic properties of water outgassed from the nucleus and icy grains may be different due to fractionation effects at sublimation. In this case, all comets may share the same Earth-like D/H ratio in water, with profound implications for the early solar system and the origin of Earth's oceans.

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Section: Correlation Between the D/h Ratio And Hyperactivitysupporting

confidence: 67%

Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets

Lis

Bockelée‐Morvan

Güsten

et al. 2019

A&A

108

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“…Densities are quite low, from a few tens to hundreds of kg/m 3 . This is in good agreement with the estimation, about 100 kg/m 3 made for dust in the coma of comet Halley (Fulle et al 2000), and even lower than the bulk density, of 537.8 ± 0.6 kg/m 3 , of the nucleus of 67P/C-G (Pätzold et al 2019).…”

Section: Composition and Physical Properties Of Cometary Dust Particlessupporting

confidence: 91%

Linking studies of tiny meteoroids, zodiacal dust, cometary dust and circumstellar disks

Levasseur-Regourd

Lasue

Milli

et al. 2020

Planetary and Space Science

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Tiny meteoroids entering the Earth's atmosphere and inducing meteor showers have long been thought to originate partly from cometary dust. Together with other dust particles, they form a huge cloud around the Sun, the zodiacal cloud. From our previous studies of the zodiacal light, as well as other independent methods (dynamical studies, infrared observations, data related to Earth's environment), it is now established that a significant fraction of dust particles entering the Earth's atmosphere comes from Jupiterfamily comets (JFCs).This paper relies on our understanding of key properties of the zodiacal cloud and of comet 67P/Churyumov-Gerasimenko, extensively studied by the Rosetta mission to a JFC. The interpretation, through numerical and experimental simulations of zodiacal light local polarimetric phase curves, has recently allowed us to establish that interplanetary dust is rich in absorbing organics and consists of fluffy particles. The ground-truth provided by Rosetta presently establishes that the cometary dust particles are rich in organic compounds and consist of quite fluffy and irregular aggregates. Our aims are as follows: (1) to make links, back in time, between peculiar micrometeorites, tiny meteoroids, interplanetary dust particles, cometary dust particles, and the early evolution of the Solar System, and (2) to show how detailed studies of such meteoroids and of cometary dust particles can improve the interpretation of observations of dust in protoplanetary and debris disks. Future modeling of dust in such disks should favor irregular porous particles instead of more conventional compact spherical particles.

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“…with a constant planetesimal bulk density ρ pla = 538 kg m −3 (Pätzold et al 2018) and the gravitational constant G. For the protoplanetary disc we apply the model of the Minimum Mass Solar Nebula, where the radial distance dependence of the gas density is described by (Hayashi 1981)…”

Section: Wind Erosion Of Pebble Pile Planetesimalsmentioning

confidence: 99%

“…τ wall /τ erosion in dependence of the planetesimal size R and its semi-major axis a for U rel = 50 m s −1 . The planetesimal density is assumed to be ρ pla = 538 kg m −3(Pätzold et al 2018) and the pebble size is assumed to be d = 1 mm. For τ wall /τ erosion > 1 erosion occurs.…”

mentioning

confidence: 99%

Planetesimals in rarefied gas: wind erosion in slip flow

Demirci

Schneider

Steinpilz

et al. 2020

Monthly Notices of the Royal Astronomical Society

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A planetesimal moves through the gas of its protoplanetary disc where it experiences a head wind. Though the ambient pressure is low, this wind can erode and ultimately destroy the planetesimal if the flow is strong enough. For the first time, we observe wind erosion in ground based and microgravity experiments at pressures relevant in protoplanetary discs, i.e. down to 10 −1 mbar. We find that the required shear stress for erosion depends on the Knudsen number related to the grains at the surface. The critical shear stress to initiate erosion increases as particles become comparable to or larger than the mean free path of the gas molecules. This makes pebble pile planetesimals more stable at lower pressure. However, it does not save them as the experiments also show that the critical shear stress to initiate erosion is very low for sub-millimetre sized grains.

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The Nucleus of comet 67P/Churyumov–Gerasimenko – Part I: The global view – nucleus mass, mass-loss, porosity, and implications

Cited by 107 publications

References 29 publications

Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets

Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets

Linking studies of tiny meteoroids, zodiacal dust, cometary dust and circumstellar disks

Planetesimals in rarefied gas: wind erosion in slip flow

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