Olivier Mousis - Academia.edu (original) (raw)

Papers by Olivier Mousis

The origin of Titan’s nitrogen-rich atmosphere is thought to be ammonia ice, but this has not yet... more The origin of Titan’s nitrogen-rich atmosphere is thought to be ammonia ice, but this has not yet been confirmed.
Furthermore, it is uncertain whether the building blocks of Titan formed within the Saturnian subnebula or in the
colder protosolar nebula (PSN). Recent measurements of the nitrogen isotope ratio in cometary ammonia, combined
with evolutionary constraints on the nitrogen isotopes in Titan’s atmosphere provide firm evidence that the nitrogen
in Titan’s atmosphere must have originated as ammonia ice formed in the PSN under conditions similar to that
of cometary formation. This result has important implications for the projected D/H ratio in cometary methane,
nitrogen isotopic fractionation in the PSN and the source of nitrogen for Earth’s atmosphere.

... Olivier; de Pater, Imke; Hammel, Heidi; Lisse, Carey; Edwards, Michelle; Sanchez-Lavega, Agus... more ... Olivier; de Pater, Imke; Hammel, Heidi; Lisse, Carey; Edwards, Michelle; Sanchez-Lavega, Agustin; Simon-Miller, Amy; Yanamandra-Fisher ... Science Institute, Boulder, CO, USA), AF(Johns Hopkins University Applied Physics Laboratory, MD, USA), AG(Gemini South Observatory ...

Phd Thesis Laboratoire De Planetologie Et Geodynamique Et Departement De Recherches Spatiales, Dec 1, 2001

Cette these est dediee a l'etude de l'origine de Titan et de son atmosphere. Dans l'hypothese ou ... more Cette these est dediee a l'etude de l'origine de Titan et de son atmosphere. Dans l'hypothese ou la subnebuleuse de Saturne etait geometriquement mince, le modele de disque turbulent utilise, derive des travaux de Dubrulle (1993), est moins dense que le modele de Prinn et Fegley (1981). De ce fait, les conversions de Co en CH4 et de N2 en NH3 ont ete inhibees dans la subnebuleuse, contrairement a ce qui est couramment admis pour interpreter la presence du methane dans l'atmosphere de Titan. C'est pourquoi nous avons developpe un nouveau scenario de la formation de titan, qui tient compte simultanement des contraintes resultant de la chimie de la subnebuleuse et des abondances de CH4, N2 et CH3D mesurees dans l'atmosphere du satellite. Nous faisons l'hypothese que ces gaz proviennent initialement de la vaporisation du nuage presolaire, qui s'effondra et forma le Soleil et son disque environnant. Lors du refroidissement de la nebuleuse, les volatils auraient ete pieges sous formes de clathrates d'hydrates dans les grains, puis dans les planetesimaux qu'ils formerent. Les planetesimaux hydrates a l'origine de la formation de Titan seraient alors des rescapes de l'effondrement hydsrodynamique de la feeding zone de Saturne. Ce scenario a ete applique aux subnebuleuses de Jupiter et d'Uranus, et a apporte un certain nombre de contraintes sur la formation des satellites reguliers de ces planetes. Le temps et la zone de formation des grains cometaires ont egalement ete estimes dans la nebuleuse solaire. Enfin, l'etude experimentale de la temperature de fusion du dihydrate d'ammoniac dans la gamme des hautes pressions a apporte des nouvelles donnees thermodynamiques qui permettront d'ameliorer les modeles de l'interieur de Titan.

Using the clathrate hydrates trapping theory, we calculate the enrichments in volatiles in the at... more Using the clathrate hydrates trapping theory, we calculate the enrichments in volatiles in the atmospheres of Jupiter and Saturn from the thermodynamical evolution of the solar nebula, in a way consistent with recent models of giant planets formation (Alibert et al. 2005a). We also discuss the influence of the recent Cassini measurement of carbon abundance in Saturn (Flasar et al. 2005) on the amount of heavy elements required in the giant planet.

The Astronomer S Telegram, Sep 1, 2006

The 1.0m telescope at Sutherland (SAAO, South-Afrika) was used to image the objects (17493) WILDC... more The 1.0m telescope at Sutherland (SAAO, South-Afrika) was used to image the objects (17493) WILDCAT, (22653) 1998 QW2, 2006 FZ51, 2006 GZ42, 2006 HH89. All of these asteroids have orbits with a Tisserand parameter close to 3, corresponding to the boundary between asteroidal and cometary orbits (Hsieh and Jewitt 2006 Science, 312, 561). Short exposure sequences of 30 to 60 seconds per frame were acquired between 2006-06-01 and 2006-06-11, giving a total exposure time of 45 to 60 minutes per object.

Astrophys J, 2005

Using the clathrate hydrates trapping theory, we discuss the enrichments in volatiles in the atmo... more Using the clathrate hydrates trapping theory, we discuss the enrichments in volatiles in the atmosphere of Jupiter measured by the Galileo probe in the framework of new extended core accretion planet formation models including migration and disk evolution. We construct a self-consistent model in which the volatile content of planetesimals accreted during the formation of Jupiter is calculated from the thermodynamical evolution of the disk. Assuming CO2:CO:CH4=30:10:1 (ratios compatible with interstellar medium measurements), we show that we can explain the enrichments in volatiles in a way compatible with the recent constraints set from internal structure modeling on the total amount of heavy elements present in the planet.

The analytical model developed in Drouart et al., (1999) for the solar nebula is used to interpre... more The analytical model developed in Drouart et al., (1999) for the solar nebula is used to interpret, through the integration of the equation of diffusion, the HCN D/H ratio observed in Hale-Bopp comet. By comparing with the D/H ratios measured in water in Halley, Hyakutake and Hale-Bopp comets, we constrain the heliocentric distance range and the time interval in which the comets of the Oort cloud were formed in the nebula. As previously shown for water (drouart et al., 1999), icy HCN grains originating from the presolar cloud and strongly enriched in deuterium with respect to the protosolar value, have been reprocessed in the nebula prior to the formation of comets. Isotopic exchange with molecular hydrogen and mixing in the turbulent nebula govern this isotopic reset. Accordingly, the presolar D/H ratio in HCN is estimated to lie between 4 and 8.10(-3) . Drouart et al., Icarus, 1999 (in press)

Egu General Assembly Conference Abstracts, Mar 1, 2009

Using a statistical model based on the theory of van der Waals and Platteeuw, we show that clathr... more Using a statistical model based on the theory of van der Waals and Platteeuw, we show that clathrate hydrates may influence the gas partionning in the atmosphere of Titan and Mars. Indeed, in January 2005, the atmospheric measurements carried out during the descent of the Huygens probe showed that, except for some tiny amounts of 36Ar, no other primordial noble gases were detected in Titan's atmosphere (their mole fractions may be smaller than the GCMS instrument's sensibility). It has been recently proposed that the formation of clathrate hydrates on the surface of Titan may act as a sink for atmospheric gases and that the trapping of noble gases in such hydrates can deeply modify their atmospheric concentration. The results of our calculations show that there is actually a strong correlation between the evolution of Titan's climate and the efficiency of the noble gases trapping in hydrates. Moreover, we find that, when the Titan's atmospheric temperature and pressure conditions decrease, the capture of Kr and Xe in hydrates becomes more efficient, whereas that of Ar diminishes. Moreover, recent observations have evidenced traces of methane (CH4) heterogeneously distributed in the Martian atmosphere. However, because the lifetime of CH4 in the atmosphere of Mars is estimated to be around 250-430 years on the basis of gas-phase chemistry, its actual sources on Mars remain controversial. Among other assumptions, it has been proposed that clathrate hydrates located in the subsurface of Mars could be at the origin of the small quantities of CH4 detected. Our results show that methane enriched clathrate hydrates could be stable in the subsurface of Mars only if a primitive CH4-rich atmosphere has existed or if a subsurface source of CH4 has been (or is still) present.

Sf2a 2005 Semaine De L Astrophysique Francaise, Dec 1, 2005

We present an evolutionary turbulent model of the Jovian subnebula consistent with the extended c... more We present an evolutionary turbulent model of the Jovian subnebula consistent with the extended core accretion formation models of Jupiter described by Alibert et al. (2005a). We calculate the thermodynamical conditions inside the subnebula, and the migration of proto-satellites. By tempting to reproduce the location vs. ice content of the Jovian satellites, we obtain constraints on the dissipation parameter inside the subnebula.

We examine the implications of collisional effects on the physical and chemical differentiation o... more We examine the implications of collisional effects on the physical and chemical differentiation of the planetesimals located in the primitive Edgeworth-Kuiper Belt. Results show changes in the initial composition only in the subsurface layers.

The trapping of volatile species in the form of clathrate hydrates during the formation of icy pl... more The trapping of volatile species in the form of clathrate hydrates during the formation of icy planetesimals in the outer solar nebula is a realistic mechanism to interpret the volatile enrichments observed in the giant planets. However, up until now, some ad hoc assumptions have been made in the scenarios using clathration as the main process to allow the trapping of volatiles in the solar nebula gas-phase. In particular, the clathration process is always assumed to be fully efficient. Moreover, the abundance of oxygen is still considered as a free parameter adjusted in order to provide enough water to trap as clathrate hydrate the required volatile species in the outer nebula. In this work, we address these shortcomings and we demonstrate that it is possible to fit the volatile enrichments in Jupiter and Saturn by postulating a partial efficiency of the clathration process and using an oxygen solar abundance. We also show that the volatile species that are not trapped via clathration crystallize as pure condensates at the temperature and pressure conditions of the outer solar nebula. Icy planetesimals formed in the outer nebula then incorporate volatiles trapped both in the form of clathrate hydrates and pure condensates. We finally show that the resulting quantities of volatiles contained within the envelopes of Jupiter and Saturn are compatible with the amounts of heavy elements (ices + rocks) predicted by their internal structure models.

Egu General Assembly Conference Abstracts, Apr 29, 2010

We investigate here the sensitivity of gas hydrate occupancies predicted on the basis of van der ... more We investigate here the sensitivity of gas hydrate occupancies predicted on the basis of van der Waals-Platteeuw theory, as a function of the treatment of the intermolecular guest-water interaction potential. First, we determine the minimum number of water molecules that have to be taken into account in the calculations of this interaction potential. We show that analytical correction terms that account for the interactions with the water molecules beyond the cutoff distance (typically chosen to take into account at least 4 water layers around the guest molecule) must be introduced to improve significantly the convergence rate, and hence the efficiency of the computation of the Langmuir constants. Then we use different recent guest-water interaction potential models to calculate the cage occupancies in pure methane or carbon dioxide clathrates. We show that the corresponding predicted cage occupancies can vary significantly depending on the model, although all the results are within the uncertainties of the available experimental data. That sensitivity becomes especially strong in the case of multiple guest clathrates, and, for instance, the results obtained for guest clathrate hydrates potentially formed on the surface of Mars can vary by more than two orders of magnitude depending on the model. These results underline the strong need for experimental data on pure and multiple guest clathrate hydrates, in particular in the temperature and pressure range that are relevant in extreme environment conditions, to discriminate among the theoretical models.

Science advances, 2015

Comets have been considered to be representative of icy planetesimals that may have contributed a... more Comets have been considered to be representative of icy planetesimals that may have contributed a significant fraction of the volatile inventory of the terrestrial planets. For example, comets must have brought some water to Earth. However, the magnitude of their contribution is still debated. We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft. Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope (36)Ar and by the (36)Ar/(38)Ar ratio. Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given. Nevertheless, this range confirms that comets of the type 67P/Churyumov-Gerasimenko cannot be the major source of Earth'...

In recent years, broadband colors on trans-Neptunian objects (TNOs) have greatly increased the kn... more In recent years, broadband colors on trans-Neptunian objects (TNOs) have greatly increased the knowledge of their surface properties. With the large and high quality color available datasets, strong and significant results have been found. We present here the last B-V, V-R and R-I color measurements obtained with the CFH12K mosaic camera of the 3.6m Canada-France-Hawaii Telescope (CFHT). This work is the latest extension of the Meudon Multicolor Survey (2MS) that totalizes now a dataset of 70 Centaurs and TNOs. In previous work (Doressoundiram et al., 2002, AJ, 124, 2279-2296), we found significant correlations between optical colors and some orbital parameters (i, e, q) for the Classical Kuiper Belt. On the other hand, no clear trend was obvious for Plutinos, Scattered objects or Centaurs. In this new and larger dataset, we looked for confirmation of the correlations found and possible detection of new significant trends for populations previously under sampled (e.g. scattered disk objects). We make also some comparison with related populations (e.g. irregular satellites, cometary nuclei). This analysis will be presented and discussed.

37Th Annual Lunar and Planetary Science Conference, 2006

We calculate the structure and the evolution of the Saturn's subnebula, in a way consistent with ... more We calculate the structure and the evolution of the Saturn's subnebula, in a way consistent with the formation process of the planet, by using a two-dimensional evolutionary turbulent alpha-model. We also discuss the implications for the formation of Titan in the subnebula.

White Oval BA, constituted from 3 predecessor vortices (known as Jupiter&amp;amp;amp;amp;... more White Oval BA, constituted from 3 predecessor vortices (known as Jupiter&amp;amp;amp;amp;#39;s &amp;amp;amp;amp;quot;classical&amp;amp;amp;amp;quot; White Ovals) after successive mergers in 1998 and 2000, became second-largest vortex in the atmosphere of Jupiter (and possibly the solar system) at the time of its formation. While it continues in this distinction,it required a name change after a 2005 December through 2006 February transformation which made