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Laboratory data and modeling of Pluto’s spectra

Laboratory data and modeling of Pluto’s spectra. Bernard Schmitt Eric Quirico, Sylvain Douté et Olivier Brissaud. Laboratoire de Planétologie de Grenoble, CNRS - Université J. Fourier Bernard.Schmitt@obs.ujf-grenoble.fr. Schmitt et al., 1998, Solar System Ices, p.199.

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Laboratory data and modeling of Pluto’s spectra

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  1. Laboratory data and modeling of Pluto’s spectra Bernard Schmitt Eric Quirico, Sylvain Douté et Olivier Brissaud Laboratoire de Planétologie de Grenoble, CNRS - Université J. Fourier Bernard.Schmitt@obs.ujf-grenoble.fr

  2. Schmitt et al., 1998, Solar System Ices, p.199 Optical properties of ices

  3. Mesurement of spectral properties (0,4 – 200 µm) of molecular solids Infrared Spectrometer with an optical cryogenic system (10 - 300 K) • Solids : • - Ices • Clathrates, Hydrates, • Organics, • Minerals, … • Study effects of: • Temperature • Phases • Composition • Compounds • UV irradiations

  4. Ices, organics, …Near and mid-infrared

  5. Nitrogen 2n • 2 phases • Transition : 35.6K • - 2 very weak bands • - Very sensitive to phase • - Sensitive to temperature • Fundamental band sensitive to CO2, H2O • Spectral shape •  surface thermometer n Grundy et al., 1993, Icarus, 105, 254 Schmitt et al., 1998, Solar System Ices, 199

  6. Methane Vis Near-IR Mid-IR • Very large number of bands of various intensities, down to the visible range • - Band shape sensitive to temperature Grundy et al., 2002, Icarus, 155, 486

  7. Methane

  8. CH4 – N2 mixtures • Spectra very sensitive on the way the molecular mixture is formed • Crystal growth from the liquid under thermodynamic equilibrium best represent the surface of Pluton and Triton ! Schmitt et al., 1998, Solar System Ices, 199

  9. Diluted CH4 – N2 mixtures CH4 spectrum sensitive to : - Pure vs diluted - N2 phase and temperature - CH4 abundance (> 2%) Quirico & Schmitt 1997a Icarus, 127, 354

  10. Rich CH4 – N2 mixtures Spectrum = combination of the spectra of the saturated N2:CH4 solutions Quirico et al; 1996 PSS, 44, 973 Schmitt et al., 1998, Solar System Ices, 199

  11. Water ice Amorphous phase : Spectrum slightly depend on temperature - Similar to high temperature crystalline Crystalline phase : Strong dependence with temperature, especially @ 1.65 µm band  H2O ice thermometer Schmitt et al., 1998, Solar System Ices, 199

  12. Water ice : Phase and temperature Grundy et al., 1998, JGR E, 103, 25809

  13. Ammonia Pure ammonia : - Several phases Ammonia hydrates: - 3 hydrate types + several phases  Complex spectra and not yet well studied (in course …) Schmitt et al., 1998, Solar System Ices, 199

  14. Simple hydrocarbons Quirico & Schmitt 1997a Icarus, 127, 354

  15. Carbon monoxyde 2n 3n Quirico & Schmitt 1997a Icarus, 127, 354 Quirico & Schmitt 1997a Icarus, 128, 181

  16. Carbon dioxyde - Weakly sensitive to temperature Quirico & Schmitt 1997a Icarus, 127, 354

  17. Methanol, nitriles, oxydes, … Many molecules measured or under study : CH3OH, HC3N, C3H4, C2H5CN, C6H6, C3N3H3, …

  18. Mesure de la réflectance spectrale (0,3 – 4,8 µm) bidirectionnelle des surfaces granulaires • Etude effets de la : • - Composition, • - Taille et forme des grains, • - Rugosité de surface, • Indices optiques, … • Mesure spectres et fonctions de diffusion : • - Glaces, minéraux, • - Organiques, • - Matériaux géophysiques, • Applications : • Spectro-imagerie spatiale

  19. yellow tholins poly-HCN black tholins C-H-N compounds • Visible slope and near-IR band strength sensitive to composition and structure of the macromolecular solid Reflectance Wavelength (nm) Bernard et al. 2006, Icarus 185, 301 samples from LISA

  20. surfaces par spectro-imagerie • Composition • Identification de molécules • Etat physique • Modes de coexistence • Abondances • Distribution spatiale • Variations temporelles • Origine - Evolutions • Origine chimique des molécules • Complexité de la matière organique • Microphysique échanges surface/atmosphère • Transports (cycles jour, saison, climat, …) • Liens avec géologie, topographie, …

  21. Molecules identification Quirico et al. 1999 Icarus, 139, 159

  22. Physical state Quirico et al. 1999 Icarus, 139, 159

  23. Distribution, abundance, grain size • Different ways of mixing : • Molecular • Compounds • Granular • Spatial • Stratigraphy (tholins) Douté et al. 1999 Icarus, 142, 421

  24. Complete modeling • Comparison between objects

  25. New-Horizon : spatial distribution Quirico et al. 1999 Icarus, 139, 159

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