67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio

Altwegg, Kathrin; Balsiger, H.; Bar‐Nun, A.; Berthelier, Jean‐Jacques; Bieler, André; Bochsler, P.; Briois, C.; Calmonte, Ursina; Combi, M. R.; Keyser, Johan De; Eberhardt, P.; Fiethe, B.; Fuselier, S. A.; Gombosi, T. I.; Hansen, K. C.; Hässig, Myrtha; Jäckel, A.; Kopp, E.; Korth, A.; LeRoy, L.; Mall, U.; Marty, Bernard; Mousis, O.; Neefs, Eddy; Owen, Tobias; Rème, H.; Rubin, Martin; Sémon, Thierry; Tzou, Chia-Yu; Waite, Hunter; Würz, Peter

doi:10.1126/science.1261952

Cited by 466 publications

(348 citation statements)

References 25 publications

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“…This value is compatible with VSMOW and more than 3 times lower than predicted by Kavelaars et al (2011). Lis et al (2013) (Altwegg et al 2015). Figure 4 summarizes measurements of the D/H ratio in water and hydrogen throughout the solar system.…”

Section: Water and D/hsupporting

confidence: 62%

“…Brasser and Morbidelli (2013) suggest, however, that JFCs and OCCs originated from the same extended outer region of the PSN. This would mean that comets like Hartley 2, which has a lower D/H, formed closer to the Sun and comets with a higher D/H, like 67P/Churyumov-Gerasimenko (hereafter 67P/CG) formed farther out (Altwegg et al 2015). This is consistent with the scenario suggesting that the migration of the young Jupiter and Saturn towards the inner solar system and back, caused mixing of material over large heliocentric distances (Walsh et al 2011) causing the original D/H gradient with heliocentric distance to completely vanish and allow similar D/H ratios in both comet families.…”

Section: Water and D/hmentioning

confidence: 99%

“…The observed features will reflect the process that formed them (e.g. water ice and Cometary 16 O/ 18 O ratios from water of 518 ± 45 and 470 ± 70 at Halley (Balsiger et al 1995;Eberhardt et al 1995) and 556 ± 70 at 67P/CG (Altwegg et al 2015) have been obtained by mass spectroscopy and 530 ± 50 by radio band spectroscopic remote sensing (Lecacheux et al 2003;Biver et al 2007 (Hutsemékers et al 2008). Non-water-group measurements have been made from direct sampling of the mineral grains returned from 81P/Wild2 by Stardust, 490-520 (McKeegan et al 2006).…”

Section: Oxygen Isotopesmentioning

confidence: 99%

“…Direct detection from mass spectroscopy can be more effective, but the opportunities in comets are limited to the few JFCs that have been visited by spacecraft (e.g. Balsiger et al 1995;Eberhardt et al 1995;Altwegg and Bockelée-Morvan 2003;Altwegg et al 2015).…”

Section: C H O and Nmentioning

confidence: 99%

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Constraints from Comets on the Formation and Volatile Acquisition of the Planets and Satellites

et al. 2015

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Comets play a dual role in understanding the formation and evolution of the solar system. First, the composition of comets provides information about the origin of the giant planets and their moons because comets formed early and their composition is not expected to have evolved significantly since formation. They, therefore serve as a record of conditions during the early stages of solar system formation. Once comets had formed, their orbits were perturbed allowing them to travel into the inner solar system and impact the planets. In this way they contributed to the volatile inventory of planetary atmospheres. We review here how knowledge of comet composition up to the time of the Rosetta mission has contributed to understanding the formation processes of the giant planets, their moons and small icy bodies in the solar system. We also discuss how comets contributed to the volatile inventories of the giant and terrestrial planets.

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Section: Water and D/hsupporting

confidence: 62%

Section: Water and D/hmentioning

confidence: 99%

Section: Oxygen Isotopesmentioning

confidence: 99%

Section: C H O and Nmentioning

confidence: 99%

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Constraints from Comets on the Formation and Volatile Acquisition of the Planets and Satellites

et al. 2015

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“…The D/H ratio in cometary water is calculated from a comparison of calibrated intensities of spectroscopic or spectrometric peaks for isotopic variants of water-derived species, e.g., H 2 DO + /H 3 O + (Balsiger et al 1995), HDO/H 2 O (Hartogh et al 2011;Lis et al 2013;Altwegg et al 2015), and OD/OH (Hutsemékers et al 2008). Though measured in the gaseous coma, the D/H ratio is assumed to be identical to that of the ice.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Deuterium Enrichment in Cometary Water via Eley–rideal Reactions

Yao

Giapis

2017

ApJ

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The deuterium-to-hydrogen ratio (D/H) in water found in the coma of Jupiter family comet (JFC) 67P/ Churyumov-Gerasimenko was reported to be (5.3±0.7)×10 −4 , the highest among comets and three times the value for other JFCs with an ocean-like ratio. This discrepancy suggests the diverse origins of JFCs and clouds the issue of the origin of Earth's oceanic water. Here we demonstrate that Eley-Rideal reactions between accelerated water ions and deuterated cometary surface analogs can lead to instantaneous deuterium enrichment in water scattered from the surface. The reaction proceeds with H 2 O + abstracting adsorbed D atoms, forming an excited H 2 DO * state, which dissociates subsequently to produce energetic HDO. Hydronium ions are also produced readily by the abstraction of H atoms, consistent with H 3 O + detection and abundance in various comets. Experiments with water isotopologs and kinematic analysis on deuterated platinum surfaces confirmed the dynamic abstraction mechanism. The instantaneous fractionation process is independent of the surface temperature and may operate on the surface of cometary nuclei or dust grains, composed of deuterium-rich silicates and carbonaceous chondrites. The requisite energetic water ions have been detected in the coma of 67P in two populations. This dynamic fractionation process may temporarily increase the water D/H ratio, especially as the comet gets closer to the Sun. The magnitude of the effect depends on the water ion energy-flux and the deuterium content of the exposed cometary surfaces.

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Photochemistry of forbidden oxygen lines in the inner coma of 67P/Churyumov‐Gerasimenko

et al. 2016

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Observations of the green and red‐doublet emission lines have previously been realized for several comets. We present here a chemistry‐emission coupled model to study the production and loss mechanisms of the O(1S) and O(1D) states, which are responsible for the emission lines of interest for comet 67P/Churyumov‐Gerasimenko. The recent discovery of O2 in significant abundance relative to water 3.80 ± 0.85% within the coma of 67P has been taken into consideration for the first time in such models. We evaluate the effect of the presence of O2 on the green to red‐doublet emission intensity ratio, which is traditionally used to assess the CO2 abundance within cometary atmospheres. Model simulations, solving the continuity equation with transport, show that not taking O2 into account leads to an underestimation of the CO2 abundance within 67P, with a relative error of about 25%. This strongly suggests that the green to red‐doublet emission intensity ratio alone is not a proper tool for determining the CO2 abundance, as previously suggested. Indeed, there is no compelling reason why O2 would not be a common cometary volatile, making revision of earlier assessments regarding the CO2 abundance in cometary atmospheres necessary. The large uncertainties of the CO2 photodissociation cross section imply that more studies are required in order to better constrain the O(1S) and O(1D) production through this mechanism. Space weather phenomena, such as powerful solar flares, could be used as tools for doing so, providing additional information on a good estimation of the O2 abundance within cometary atmospheres.

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67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio

Cited by 466 publications

References 25 publications

Constraints from Comets on the Formation and Volatile Acquisition of the Planets and Satellites

Constraints from Comets on the Formation and Volatile Acquisition of the Planets and Satellites

Dynamic Deuterium Enrichment in Cometary Water via Eley–rideal Reactions

Photochemistry of forbidden oxygen lines in the inner coma of 67P/Churyumov‐Gerasimenko

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