Cometary Isotopic Measurements

Bockelée‐Morvan, Dominique; Calmonte, Ursina; Charnley, Steven B.; Duprat, J.; Engrand, C.; Gicquel, A.; Hässig, Myrtha; Jehin, Emmanuël; Kawakita, Hideyo; Marty, Bernard; Milam, Stefanie N.; Morse, A. D.; Rousselot, P.; Sheridan, S.; Wirström, E. S.

doi:10.1007/s11214-015-0156-9

Cited by 123 publications

(120 citation statements)

References 199 publications

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“…This is seen as a priority for future measurements, both to confirm the match between ice in MBCs and Earth's water, but also to better understand the original source region where MBCs formed. In addition to D/H, isotopic ratios in other volatile elements (O, C, N, S) are measured in comets (Jehin et al 2009;Bockelée-Morvan et al 2015). Combining information from different elements can place stronger constraints on source location within the protoplanetary disc, but these measurements are even more challenging than D/H, given the relatively low abundance of other volatile species relative to water.…”

Section: Isotopic Ratiosmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies.

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Section: Isotopic Ratiosmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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“…In contrast, remote spectroscopic measurements in comets 103P/Hartley_2 (Hartogh et al 2011) and 45P/Honda-Mrkos-Pajdusakova (Lis et al 2013) yielded a positive match, suggesting that Jupiter family comets (JFCs) may be the primary carriers of extraterrestrial water to the oceans. This notion was undermined recently by in situ measurements in the coma of another JFC, 67P/Churyumov-Gerasimenko , which yielded a water D/H ratio more than three times the SMOW and even higher than that for OCCs, thus challenging new theories on the origin of comets and supporting earlier models of deuterium distribution in the early solar system (Bockelée-Morvan et al 2015;Mandt et al 2015).…”

Section: Introductionmentioning

confidence: 97%

“…The current consensus is that at least some terrestrial water originated elsewhere in the solar system and was delivered to Earth by asteroids or comets (Robert 2001;Alexander et al 2012;Ceccarelli et al 2014). The criterion for determining whether a family of extra-terrestrial objects may have contributed to terrestrial water is the deuterium-tohydrogen ratio (D/H) in water found on the object (Bockelée- Morvan et al 2015;Mandt et al 2015). A match with the standard mean oceanic water (SMOW) ratio of 1.56×10 −4 is considered a positive, which is true for some meteorites originating from the outer asteroid belt (Alexander et al 2012).…”

Section: Introductionmentioning

confidence: 99%

“…A match with the standard mean oceanic water (SMOW) ratio of 1.56×10 −4 is considered a positive, which is true for some meteorites originating from the outer asteroid belt (Alexander et al 2012). Measurements of the D/H ratio for several Oort cloud comets (OCCs) show a value about twice as high as the SMOW, precluding OCCs as the source of Earth's water (Bockelée-Morvan et al 2015). In contrast, remote spectroscopic measurements in comets 103P/Hartley_2 (Hartogh et al 2011) and 45P/Honda-Mrkos-Pajdusakova (Lis et al 2013) yielded a positive match, suggesting that Jupiter family comets (JFCs) may be the primary carriers of extraterrestrial water to the oceans.…”

Section: Introductionmentioning

confidence: 99%

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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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“…The 14 N/ 15 N ratios measured in comets also show high enrichments in 15 N (Mumma & Charnley 2011;Bockelée-Morvan et al 2015). While the processes of nitrogen fractionation responsible for this variation are still under debate (Füri & Marty 2015), one possibility is disequilibrium ionmolecule reactions in cold, dense regions of the presolar nebula (e.g., Terzieva & Herbst 2000;Rodgers & Charnley 2008).…”

Section: Introductionmentioning

confidence: 98%

Doubly¹⁵N-substituted diazenylium: THz laboratory spectra and fractionation models

Dore

Bizzocchi

Wirström

et al. 2017

A&A

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Context. Isotopic fractionation in dense molecular cores has been suggested as a possible origin of large 14 N/ 15 N ratio variations in solar system materials. While chemical models can explain some observed variations with different fractionation patterns for molecules with -NH or -CN functional groups, they fail to reproduce the observed ratios in diazenylium (N 2 H + ). Aims. Observations of doubly15 N-substituted species could provide important constraints and insights for theoretical chemical models of isotopic fractionation. However, spectroscopic data are very scarce. Methods. The rotational spectra of the fully 15 N-substituted isopologues of the diazenylium ion, 15 N 2 H + and 15 N 2 D + , have been investigated in the laboratory well into the THz region by using a source-modulation microwave spectrometer equipped with a negative glow discharge cell. An extended chemical reaction network has been used to estimate what ranges of 15 N fractionation in doubly 15 N-substituted species could be expected in the interstellar medium (ISM). Results. For each isotopologue of the H-and D-containing pair, nine rotational transitions were accurately measured in the frequency region 88 GHz-1.2 THz. The analysis of the spectrum provided very precise rest frequencies at millimeter and sub-millimeter wavelengths, useful for the radioastronomical identification of the rotational lines of 15 N 2 H + and 15 N 2 D + in the ISM.

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Cometary Isotopic Measurements

Cited by 123 publications

References 199 publications

The Main Belt Comets and ice in the Solar System

The Main Belt Comets and ice in the Solar System

Dynamic Deuterium Enrichment in Cometary Water via Eley–rideal Reactions

Doubly¹⁵N-substituted diazenylium: THz laboratory spectra and fractionation models

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Cometary Isotopic Measurements

Cited by 123 publications

References 199 publications

The Main Belt Comets and ice in the Solar System

The Main Belt Comets and ice in the Solar System

Dynamic Deuterium Enrichment in Cometary Water via Eley–rideal Reactions

Doubly15N-substituted diazenylium: THz laboratory spectra and fractionation models

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Doubly¹⁵N-substituted diazenylium: THz laboratory spectra and fractionation models