On the origin of O<sub>2</sub> and other volatile species in comets

Taquet, V.; Furuya, Kenji; Walsh, Catherine; Dishoeck, E. F. van

doi:10.1017/s1743921317007414

Cited by 5 publications

(8 citation statements)

References 33 publications

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“…-Similar conclusions arise from the abundant amounts of O 2 , which were well correlated to H 2 O in 67P/C-G (Bieler et al 2015a). O 2 has a presolar or molecular cloud origin and formed either through cold temperature chemistry (Taquet et al 2017) and/or radiolysis (Mousis et al 2016b). Chemical formation requires slightly increased formation temperatures (∼20 K) and gas densities (n H 10 5 cm −3 ), similar to the case of the dense core ρ Ophiuchus A, but warmer compared to the lower mass environment expected for the early Sun.…”

Section: Discussionsupporting

confidence: 55%

On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko

et al. 2020

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Primitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth-and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices and thus indicate that common processes and conditions were involved in their formation. The samples returned by the Stardust mission to comet Wild 2 showed that the bulk refractory material was processed by high temperatures in the vicinity of the early sun. The recent Rosetta mission acquired a wealth of new data on the composition of comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) and complemented earlier observations of other comets. The isotopic, elemental, and molecular abundances of the volatile, semivolatile, and refractory phases brought many new insights into the origin and processing of the incorporated material. The emerging picture after Rosetta is that at least part of the volatile material was formed before the solar system and that cometary nuclei agglomerated over a wide range of heliocentric distances, different from where they are found today. Deviations from bulk solar system abundances indicate that the material was not fully homogenized at the location of comet formation, despite the radial mixing implied by the Stardust results. Post-formation evolution of the material might play an important role, which further

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Section: Discussionsupporting

confidence: 55%

On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko

et al. 2020

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“…This detection opens new scenarios and raises interest in the possibility of detecting molecular oxygen in cometary and interstellar ice. Recent work by Taquet et al (2016) show that solid O 2 , with a molecular ratio to water ice similar to those measured in comet 67P, can be produced in molecular clouds with relatively low H to O abundance ratio in the gas phase, high densities (≥10 5 cm −3 ) and dust temperature around 20 K, higher than that typically measured in interstellar dark clouds (10-15 K).…”

Section: Introductionmentioning

confidence: 65%

O₂ signature in thin and thick O₂−H₂O ices

Müller

Giuliano

Bizzocchi

et al. 2018

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Aims. In this paper we investigate the detectability of the molecular oxygen in icy dust grain mantles towards astronomical objects. Methods. We present a systematic set of experiments with O2−H2O ice mixtures designed to disentangle how the molecular ratio affects the O2 signature in the mid- and near-infrared spectral regions. All the experiments were conducted in a closed-cycle helium cryostat coupled to a Fourier transform infrared spectrometer. The ice mixtures comprise varying thicknesses from 8 × 10−3 to 3 μm. The absorption spectra of the O2−H2O mixtures are also compared to the one of pure water. In addition, the possibility to detect the O2 in icy bodies and in the interstellar medium is discussed. Results. We are able to see the O2 feature at 1551 cm−1 even for the most diluted mixture of H2O:O2 = 9:1, comparable to a ratio of O2/H2O = 10% which has already been detected in situ in the coma of the comet 67P/Churyumov-Gerasimenko. We provide an estimate for the detection of O2 with the future mission of the James Webb Space Telescope (JWST).

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“…The preservation of the inner layers of the icy grain mantles from the dark cloud stage until their incorporation into cometary nuclei is supported by the observation of a distributed source of halogens in the coma of 67P/C-G (Dhooghe et al 2017). Thus, the scenario of O 2 production and the subsequent evolution of ice during the transition from dark cloud to protoplanetary disk discussed in Taquet et al (2016) and Taquet et al (2017) is consistent with observations of other volatiles (such as N 2 and CO) made at 67P/C-G.…”

Section: Recombination Of Oxygen Atoms On the Surfaces Of Interstellamentioning

confidence: 77%

“…Contrary to O 2 , CO and N 2 mostly form in the outermost layers of the icy mantle. Taquet et al (2017) detail the impact of layering of the icy mantle during the transition from dark cloud to protoplanetary disk and its consequences to the volatile content of cometary ices. The outer layers of the icy grains are more likely to evaporate in the outer layer of the protoplanetary disk releasing N 2 and CO in the gas phase, while the inner ice layers where most of the O 2 would be trapped remains frozen.…”

Section: Recombination Of Oxygen Atoms On the Surfaces Of Interstellamentioning

confidence: 99%

Origin of Molecular Oxygen in Comets: Current Knowledge and Perspectives

et al. 2018

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The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard the Rosetta spacecraft has measured molecular oxygen (O 2) in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) in surprisingly high abundances. These measurements mark the first unequivocal detection of O 2 in a cometary environment. The large relative abundance of O 2 in 67P/C-G despite its high reactivity and low interstellar abundance poses a puzzle for its origin in comet 67P/C-G, and potentially other comets. Since its detection, there have been a number of hypotheses put forward to explain the production and origin of O 2 in the comet. These hypotheses cover a wide range of possibilities from various in situ production mechanisms to protosolar nebula and primordial origins. Here, we review the O 2 formation mechanisms from the literature, and provide a comprehensive summary of the current state of knowledge of the sources and origin of cometary O 2 .

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On the origin of O₂ and other volatile species in comets

Cited by 5 publications

References 33 publications

On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko

On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko

O₂ signature in thin and thick O₂−H₂O ices

Origin of Molecular Oxygen in Comets: Current Knowledge and Perspectives

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On the origin of O2 and other volatile species in comets

Cited by 5 publications

References 33 publications

On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko

On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko

O2 signature in thin and thick O2−H2O ices

Origin of Molecular Oxygen in Comets: Current Knowledge and Perspectives

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On the origin of O₂ and other volatile species in comets

O₂ signature in thin and thick O₂−H₂O ices