35 research outputs found
Triton Haze Analogs: The Role of Carbon Monoxide in Haze Formation
Triton is the largest moon of the Neptune system and possesses a thin nitrogen atmosphere with trace amounts of carbon monoxide and methane, making it of similar composition to that of the dwarf planet Pluto. Like Pluto and Saturn\u27s moon Titan, Triton has a haze layer thought to be composed of organics formed through photochemistry. Here, we perform atmospheric chamber experiments of 0.5% CO and 0.2% CH4 in N2 at 90 K and 1 mbar to generate Triton haze analogs. We then characterize the physical and chemical properties of these particles. We measure their production rate, their bulk composition with combustion analysis, their molecular composition with very high resolution mass spectrometry, and their transmission and reflectance from the optical to the near-infrared with Fourier Transform Infrared (FTIR) Spectroscopy. We compare these properties to existing measurements of Triton\u27s tenuous atmosphere and surface, as well as contextualize these results in view of all the small, hazy, nitrogen-rich worlds of our solar system. We find that carbon monoxide present at greater mixing ratios than methane in the atmosphere can lead to significantly oxygen- and nitrogen-rich haze materials. These Triton haze analogs have clear observable signatures in their near-infrared spectra, which may help us differentiate the mechanisms behind haze formation processes across diverse solar system bodies
COSIMA-Rosetta calibration for in-situ characterization of 67P/Churyumov-Gerasimenko cometary inorganic compounds
20 pages, 3 figures, 5 tablesInternational audienceCOSIMA (COmetary Secondary Ion Mass Analyser) is a time-of-flight secondary ion mass spectrometer (TOF-SIMS) on board the Rosetta space mission. COSIMA has been designed to measure the composition of cometary dust grains. It has a mass resolution m/{\Delta}m of 1400 at mass 100 u, thus enabling the discrimination of inorganic mass peaks from organic ones in the mass spectra. We have evaluated the identification capabilities of the reference model of COSIMA for inorganic compounds using a suite of terrestrial minerals that are relevant for cometary science. Ground calibration demonstrated that the performances of the flight model were similar to that of the reference model. The list of minerals used in this study was chosen based on the mineralogy of meteorites, interplanetary dust particles and Stardust samples. It contains anhydrous and hydrous ferromagnesian silicates, refractory silicates and oxides (present in meteoritic Ca-Al-rich inclusions), carbonates, and Fe-Ni sulfides. From the analyses of these minerals, we have calculated relative sensitivity factors for a suite of major and minor elements in order to provide a basis for element quantification for the possible identification of major mineral classes present in the cometary grains
Carbon-rich dust in comet 67P/Churyumov-Gerasimenko measured by COSIMA/Rosetta
Cometary ices are rich in CO2, CO and organic volatile
compounds, but the carbon content of cometary dust was only measured for
the Oort Cloud comet 1P/Halley, during its flyby in 1986. The COmetary
Secondary Ion Mass Analyzer (COSIMA)/Rosetta mass spectrometer
analysed dust particles with sizes ranging from 50 to 1000Â ÎŒm, collected
over 2 yr, from 67P/Churyumov-Gerasimenko (67P), a Jupiter family
comet. Here, we report 67P dust composition focusing on the elements C
and O. It has a high carbon content (atomic | |â )
close to the solar value and comparable to the 1P/Halley data. From
COSIMA measurements, we conclude that 67P particles are made of nearly
50 per cent organic matter in mass, mixed with mineral phases that are
mostly anhydrous. The whole composition, rich in carbon and non-hydrated
minerals, points to a primitive matter that likely preserved its
initial characteristics since the comet accretion in the outer regions
of the protoplanetary disc.</p
Nitrogen-to-carbon atomic ratio measured by COSIMA in the particles of comet 67P/ChuryumovâGerasimenko
The COmetary Secondary Ion Mass Analyzer (COSIMA) on board the Rosetta mission has analysed numerous cometary dust particles collected at very low velocities (a few m sâ1)
in the environment of comet 67P/ChuryumovâGerasimenko (hereafter 67P).
In these particles, carbon and nitrogen are expected mainly to be part
of the organic matter. We have measured the nitrogen-to-carbon (N/C)
atomic ratio of 27 cometary particles. It ranges from 0.018 to 0.06 with
an averaged value of 0.035 ± 0.011. This is compatible with the
measurements of the particles of comet 1P/Halley and is in the lower
range of the values measured in comet 81P/Wild 2 particles brought back
to Earth by the Stardust mission. Moreover, the averaged value
found in 67P particles is also similar to the one found in the insoluble
organic matter extracted from CM, CI and CR carbonaceous chondrites and
to the bulk values measured in most interplanetary dust particles and
micrometeorites. The close agreement of the N/C atomic ratio in all
these objects indicates that their organic matters share some
similarities and could have a similar chemical origin. Furthermore,
compared to the abundances of all the detected elements in the particles
of 67P and to the elemental solar abundances, the nitrogen is depleted
in the particles and the nucleus of 67P as was previously inferred also
for comet 1P/Halley. This nitrogen depletion could constrain the
formation scenarios of cometary nuclei.</p
Empreinte moléculaire des processus post-accrétionnels dans la matiÚre organique des chondrites carbonées
Type 1 and 2 carbonaceous chondrites include the most chemically and petrologically pristine meteorites. This intactness goes along with the abundance of organic matter which is a phase of choice to investigate the presolar material processing in the nebula and then on the first bodies. The purpose of this thesis is to study the influence of post-accretional processes on the molecular characteristics of organic matter and in particular the extent of oxidation effects due to aqueous alteration. We have carried out a comparative study based on the carbon structure and functional analysis of more than ten meteorites whose geologic histories were independently determined. The redox degree of sulfur in the insoluble fraction was measured by SK-Xanes spectroscopy. FT-IR spectroscopy gave access to the fine structures of aliphatic chains and oxygen-rich functions. Orbitrap very high resolution mass spectrometry was used to describe the heteroatomic diversity of soluble molecules in the Renazzo (CR2) chondrite. The aliphatic chains of CI chondrites and Murchison differ from others by a higher and unchanging abundance of methyl groups. Type 1 chondrites are the only carriers of oxidized sulfur functions whereas the sulfur speciation in type 2 chondrites is invariable. For all studied chondrites, the carbonyl groups are mainly under the form of ketones and their abundance canât be related to the degree of aqueous alteration. Any parameters we have measured in this study lead us to conclude that the molecular variability among type 1 and 2 carbonaceous chondrites are less due to the footprint left by the hydrothermal activity than due to the heterogeneity of an organic precursor accreted by each parent body. In particular, our measurements invalidate the hypothesis that the alteration would cause an oxidative conversion of aliphatic chains to carboxylic acid functions.Les chondrites carbonĂ©es de type 1 et 2 comprennent les mĂ©tĂ©orites les plus primitives dâun point de vue chimique et pĂ©trologique. Ce caractĂšre primitif est associĂ© Ă lâabondance de matiĂšre organique qui est une phase privilĂ©giĂ©e pour lâĂ©tude des phĂ©nomĂšnes concernant lâhĂ©ritage du matĂ©riel prĂ©solaire et sa transformation dans la nĂ©buleuse puis sur les premiers corps. Lâobjet de cette thĂšse est lâĂ©tude de lâinfluence des processus post-accrĂ©tionnels sur les caractĂ©ristiques molĂ©culaires de la matiĂšre organique et en particulier la mesure des effets dâoxydation dus Ă lâaltĂ©ration aqueuse. Nous avons menĂ© une Ă©tude comparative basĂ©e sur la structure carbonĂ©e et lâanalyse des fonctions oxygĂ©nĂ©es et soufrĂ©es dâune dizaine de mĂ©tĂ©orites dont les histoires gĂ©ologiques ont Ă©tĂ© dĂ©terminĂ©es par ailleurs. Le degrĂ© dâoxydation du soufre, hĂ©tĂ©roatome mineur dans la fraction insoluble, a Ă©tĂ© mesurĂ© par micro-spectromĂ©trie SK-Xanes. La spectroscopie FT-IR a permis la description des structures fines des chaines carbonĂ©es et des fonctions riches en oxygĂšne, hĂ©tĂ©roatome majeur. La spectromĂ©trie de masse Ă trĂšs haute rĂ©solution Orbitrap a Ă©tĂ© utilisĂ©e pour dĂ©crire la diversitĂ© hĂ©tĂ©roatomique des molĂ©cules solubles de la chondrite Renazzo (CR2). Les chaines carbonĂ©es des chondrites de classe CI et Murchison se diffĂ©rencient de celle des autres mĂ©tĂ©orites par une abondance en groupements terminaux mĂ©thyles Ă la fois supĂ©rieure et invariable. Les chondrites de type 1 sont les seules porteuses de fonctions soufrĂ©es oxydĂ©es acides alors que la spĂ©ciation du soufre dans les chondrites de type 2 est invariable. De la mĂȘme façon, et cette fois pour lâensemble des chondrites Ă©tudiĂ©es, les groupements carbonyles sont majoritairement dans les fonctions cĂ©tones, en proportion indĂ©pendante du degrĂ© dâaltĂ©ration aqueuse. Tous les paramĂštres mesurĂ©s dans cette Ă©tude nous poussent Ă conclure que la variabilitĂ© molĂ©culaire au sein des chondrites carbonĂ©es de type 1 et 2 trouve moins son origine dans lâempreinte de lâhydrothermalisme que dans une hĂ©tĂ©rogĂ©nĂ©itĂ© du prĂ©curseur organique accrĂ©tĂ© par chaque corps parent. En particulier, nos mesures invalident lâhypothĂšse selon laquelle lâaltĂ©ration serait Ă lâorigine dâune conversion oxydative des chaines carbonĂ©es en fonctions acides carboxyliques
Primordial history of the chondritic organic matter
Les chondrites carbonĂ©es de type 1 et 2 comprennent les mĂ©tĂ©orites les plus primitives dâun point de vue chimique et pĂ©trologique. Ce caractĂšre primitif est associĂ© Ă lâabondance de matiĂšre organique qui est une phase privilĂ©giĂ©e pour lâĂ©tude des phĂ©nomĂšnes concernant lâhĂ©ritage du matĂ©riel prĂ©solaire et sa transformation dans la nĂ©buleuse puis sur les premiers corps. Lâobjet de cette thĂšse est lâĂ©tude de lâinfluence des processus post-accrĂ©tionnels sur les caractĂ©ristiques molĂ©culaires de la matiĂšre organique et en particulier la mesure des effets dâoxydation dus Ă lâaltĂ©ration aqueuse. Nous avons menĂ© une Ă©tude comparative basĂ©e sur la structure carbonĂ©e et lâanalyse des fonctions oxygĂ©nĂ©es et soufrĂ©es dâune dizaine de mĂ©tĂ©orites dont les histoires gĂ©ologiques ont Ă©tĂ© dĂ©terminĂ©es par ailleurs. Le degrĂ© dâoxydation du soufre, hĂ©tĂ©roatome mineur dans la fraction insoluble, a Ă©tĂ© mesurĂ© par micro-spectromĂ©trie SK-Xanes. La spectroscopie FT-IR a permis la description des structures fines des chaines carbonĂ©es et des fonctions riches en oxygĂšne, hĂ©tĂ©roatome majeur. La spectromĂ©trie de masse Ă trĂšs haute rĂ©solution Orbitrap a Ă©tĂ© utilisĂ©e pour dĂ©crire la diversitĂ© hĂ©tĂ©roatomique des molĂ©cules solubles de la chondrite Renazzo (CR2). Les chaines carbonĂ©es des chondrites de classe CI et Murchison se diffĂ©rencient de celle des autres mĂ©tĂ©orites par une abondance en groupements terminaux mĂ©thyles Ă la fois supĂ©rieure et invariable. Les chondrites de type 1 sont les seules porteuses de fonctions soufrĂ©es oxydĂ©es acides alors que la spĂ©ciation du soufre dans les chondrites de type 2 est invariable. De la mĂȘme façon, et cette fois pour lâensemble des chondrites Ă©tudiĂ©es, les groupements carbonyles sont majoritairement dans les fonctions cĂ©tones, en proportion indĂ©pendante du degrĂ© dâaltĂ©ration aqueuse. Tous les paramĂštres mesurĂ©s dans cette Ă©tude nous poussent Ă conclure que la variabilitĂ© molĂ©culaire au sein des chondrites carbonĂ©es de type 1 et 2 trouve moins son origine dans lâempreinte de lâhydrothermalisme que dans une hĂ©tĂ©rogĂ©nĂ©itĂ© du prĂ©curseur organique accrĂ©tĂ© par chaque corps parent. En particulier, nos mesures invalident lâhypothĂšse selon laquelle lâaltĂ©ration serait Ă lâorigine dâune conversion oxydative des chaines carbonĂ©es en fonctions acides carboxyliques.Type 1 and 2 carbonaceous chondrites include the most chemically and petrologically pristine meteorites. This intactness goes along with the abundance of organic matter which is a phase of choice to investigate the presolar material processing in the nebula and then on the first bodies. The purpose of this thesis is to study the influence of post-accretional processes on the molecular characteristics of organic matter and in particular the extent of oxidation effects due to aqueous alteration. We have carried out a comparative study based on the carbon structure and functional analysis of more than ten meteorites whose geologic histories were independently determined. The redox degree of sulfur in the insoluble fraction was measured by SK-Xanes spectroscopy. FT-IR spectroscopy gave access to the fine structures of aliphatic chains and oxygen-rich functions. Orbitrap very high resolution mass spectrometry was used to describe the heteroatomic diversity of soluble molecules in the Renazzo (CR2) chondrite. The aliphatic chains of CI chondrites and Murchison differ from others by a higher and unchanging abundance of methyl groups. Type 1 chondrites are the only carriers of oxidized sulfur functions whereas the sulfur speciation in type 2 chondrites is invariable. For all studied chondrites, the carbonyl groups are mainly under the form of ketones and their abundance canât be related to the degree of aqueous alteration. Any parameters we have measured in this study lead us to conclude that the molecular variability among type 1 and 2 carbonaceous chondrites are less due to the footprint left by the hydrothermal activity than due to the heterogeneity of an organic precursor accreted by each parent body. In particular, our measurements invalidate the hypothesis that the alteration would cause an oxidative conversion of aliphatic chains to carboxylic acid functions
Empreinte moléculaire des processus post-accrétionnels dans la matiÚre organique des chondrites carbonées
Type 1 and 2 carbonaceous chondrites include the most chemically and petrologically pristine meteorites. This intactness goes along with the abundance of organic matter which is a phase of choice to investigate the presolar material processing in the nebula and then on the first bodies. The purpose of this thesis is to study the influence of post-accretional processes on the molecular characteristics of organic matter and in particular the extent of oxidation effects due to aqueous alteration. We have carried out a comparative study based on the carbon structure and functional analysis of more than ten meteorites whose geologic histories were independently determined. The redox degree of sulfur in the insoluble fraction was measured by SK-Xanes spectroscopy. FT-IR spectroscopy gave access to the fine structures of aliphatic chains and oxygen-rich functions. Orbitrap very high resolution mass spectrometry was used to describe the heteroatomic diversity of soluble molecules in the Renazzo (CR2) chondrite. The aliphatic chains of CI chondrites and Murchison differ from others by a higher and unchanging abundance of methyl groups. Type 1 chondrites are the only carriers of oxidized sulfur functions whereas the sulfur speciation in type 2 chondrites is invariable. For all studied chondrites, the carbonyl groups are mainly under the form of ketones and their abundance canât be related to the degree of aqueous alteration. Any parameters we have measured in this study lead us to conclude that the molecular variability among type 1 and 2 carbonaceous chondrites are less due to the footprint left by the hydrothermal activity than due to the heterogeneity of an organic precursor accreted by each parent body. In particular, our measurements invalidate the hypothesis that the alteration would cause an oxidative conversion of aliphatic chains to carboxylic acid functions.Les chondrites carbonĂ©es de type 1 et 2 comprennent les mĂ©tĂ©orites les plus primitives dâun point de vue chimique et pĂ©trologique. Ce caractĂšre primitif est associĂ© Ă lâabondance de matiĂšre organique qui est une phase privilĂ©giĂ©e pour lâĂ©tude des phĂ©nomĂšnes concernant lâhĂ©ritage du matĂ©riel prĂ©solaire et sa transformation dans la nĂ©buleuse puis sur les premiers corps. Lâobjet de cette thĂšse est lâĂ©tude de lâinfluence des processus post-accrĂ©tionnels sur les caractĂ©ristiques molĂ©culaires de la matiĂšre organique et en particulier la mesure des effets dâoxydation dus Ă lâaltĂ©ration aqueuse. Nous avons menĂ© une Ă©tude comparative basĂ©e sur la structure carbonĂ©e et lâanalyse des fonctions oxygĂ©nĂ©es et soufrĂ©es dâune dizaine de mĂ©tĂ©orites dont les histoires gĂ©ologiques ont Ă©tĂ© dĂ©terminĂ©es par ailleurs. Le degrĂ© dâoxydation du soufre, hĂ©tĂ©roatome mineur dans la fraction insoluble, a Ă©tĂ© mesurĂ© par micro-spectromĂ©trie SK-Xanes. La spectroscopie FT-IR a permis la description des structures fines des chaines carbonĂ©es et des fonctions riches en oxygĂšne, hĂ©tĂ©roatome majeur. La spectromĂ©trie de masse Ă trĂšs haute rĂ©solution Orbitrap a Ă©tĂ© utilisĂ©e pour dĂ©crire la diversitĂ© hĂ©tĂ©roatomique des molĂ©cules solubles de la chondrite Renazzo (CR2). Les chaines carbonĂ©es des chondrites de classe CI et Murchison se diffĂ©rencient de celle des autres mĂ©tĂ©orites par une abondance en groupements terminaux mĂ©thyles Ă la fois supĂ©rieure et invariable. Les chondrites de type 1 sont les seules porteuses de fonctions soufrĂ©es oxydĂ©es acides alors que la spĂ©ciation du soufre dans les chondrites de type 2 est invariable. De la mĂȘme façon, et cette fois pour lâensemble des chondrites Ă©tudiĂ©es, les groupements carbonyles sont majoritairement dans les fonctions cĂ©tones, en proportion indĂ©pendante du degrĂ© dâaltĂ©ration aqueuse. Tous les paramĂštres mesurĂ©s dans cette Ă©tude nous poussent Ă conclure que la variabilitĂ© molĂ©culaire au sein des chondrites carbonĂ©es de type 1 et 2 trouve moins son origine dans lâempreinte de lâhydrothermalisme que dans une hĂ©tĂ©rogĂ©nĂ©itĂ© du prĂ©curseur organique accrĂ©tĂ© par chaque corps parent. En particulier, nos mesures invalident lâhypothĂšse selon laquelle lâaltĂ©ration serait Ă lâorigine dâune conversion oxydative des chaines carbonĂ©es en fonctions acides carboxyliques
Measured mass to stoichoimetric formula through exhaustive search
International audienceElectrospray ionisation has revolutionised mass spectrometry. Coupled to high mass resolution, it provides the stoichiometric formula of a lot of molecules in a mixture. The link between the mass spectrometry data and the chemical description relies on an interpretation of the measured masses. We present here the tools and tricks developed to exploit Orbitrap mass spectra. This piece of work focuses on the numerical method to assign a molecular formula to a measured mass. The problem is restrained to the solving of the Diophantine equation where the constant coefficients are stoichiometric groups. Peculiar case of a set of convenient groups is given with the chemical constraints it brings to the problem
Preface: Evolution of molecules in space: From interstellar clouds to protoplanetary nebulae
International audienc
Bulk chemical characteristics of soluble polar organic molecules formed through condensation of formaldehyde: Comparison with soluble organic molecules in Murchison meteorite
International audienceCarbonaceous chondrites contain up to 2 wt% organic carbon, which is present as acid and solvent insoluble solid organic matter (IOM) and solvent soluble organic matter (SOM). The extraterrestrial organic matter should record chemical processes occurred in different environments in the early history of the Solar System, and the role of parent body aqueous alteration in the synthesis or subsequent modification of IOM and SOM still requires accurate constraints. We conducted hydrothermal experiments to simulate the synthesis of organic molecules during aqueous alteration on small bodies. Bulk chemical characteristics of soluble organic matter synthesized from formaldehyde in aqueous solutions were studied to compare them with that of chondritic SOM. We found that the redox state of synthesized organic molecules depends on temperature; the molecules become richer in hydrogen at higher temperatures. This can be explained by a cross-disproportionation reaction between organic molecules and formic acid, which occurs as a side reaction of the aldol condensation and works more effectively at higher temperatures. Comparison of the bulk chemical characteristics between the synthesized molecules and SOM extracted from the Murchison meteorite with methanol shows that the soluble organic molecules in Murchison are more reduced than the synthesized molecules. Considering the temperature condition for aqueous alteration on the CM parent body that is lower than or equivalent to the experimental temperatures, the reduced nature of Murchison organic molecules requires a reducing environment for them to be formed during hydrothermal alteration or imply that processes other than hydrothermal alteration were responsible for their synthesis. In case of hydrothermal synthesis, reducing conditions might be established by the interaction between water and iron-bearing silicates or metals on the parent body