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Submillimeter Astronomy of the Solar System

Submillimeter Astronomy of the Solar System. Glenn Orton Jet Propulsion Laboratory California Institute of Technology.

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Submillimeter Astronomy of the Solar System

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  1. Submillimeter Astronomy of the Solar System Glenn Orton Jet Propulsion Laboratory California Institute of Technology

  2. Thanks for help from many!Mark Gurwell Cassini Composite Infrared Spectrometer Team Linda Brown ISO Long-Wavelength Spectrometer Solar-System Team Bryan Butler Herschel Calibration Workshop Team Todd Clancy Gary Davis Brigette Hesman Juan Pardo Gene Serabyn Linda Spilker

  3. “Submillimeter” Rigorously: 0.1 – 1.0 mm 10 – 100 cm-1 300-3000 GHz But I won’t let rigor get in the way of good science!

  4. ADVANTAGES OF SUBMILLIMETER IN SOLAR-SYSTEM EXPLORATION Plethora of molecular lines Insensitivity to optical influence of haze & dust Low continuum opacity: senses deep in atmospheres High line-center opacity: senses high in atmospheres High-resolution of line cores and wings provides simultaneous depth and temperature/abundance information Senses subsurface of rocky & icy bodies

  5. Total Lunar eclipse of July 16th, 2000 Expected behavior: Fastest temperature drop at shortest wavelengths due to less penetration. Pardo, J.R., Serabyn, E., Wiedner, M.C., Icarus, submitted.

  6. Atmosphere of Venus

  7. Pardo and Serabyn: observation of HCl and search for OCS lines in Venus

  8. Venus: submm spectra of SO2 and search for SO [SO2] ~ 2 x 10-8 [SO] < 1 x 10-9 (observations from the JCMT, Clancy et al. – to be given at the Cambridge, UK, AAS/DPS meeting)

  9. Venus: Dayside vs Nightside Mesosphere Temperature Structure rapid temperature falloff in thenightside upper atmosphere ↓ ↑ temperature inversion in daysideupperatmosphere.

  10. Surface and Atmosphere of Mars

  11. ISO/LWS Spectroscopy of Martian H2O surface H2O vmr = 3 ± 1 x 10-4 saturates ~ 13 ± 2 km optical path = 12 ± 3.5 precip. µm Burgdorf et al. 2000 Icarus 145, 79.

  12. Mars Surface Emissivity Deduced from ISO/LWS Flux (Burgdorf et al. 2000 Icarus145, 79)

  13. Mars Observations from SWAS Gurwell et al. 2000. Astrophys. J. 539, L143. resolved lines allow determination of T and H2O vapor profiles simultaneously

  14. ODIN Observations of Mars: H2O and mean Tsurface resolved lines allow determination of T and H2O vapor profiles simultaneously Biver et al. (2005) Astron & Astrophys. 435, 765.

  15. dust-free model

  16. First SMA Image with all 8 Antennas: Mars can be used to map both T(p) and Tsurf Ho et al. (2004) Astrophys J. 616, 61.

  17. Mars zonal winds derived from JCMT observations of 12CO and 13CO Doppler line shifts (Clancy et al. 2005). Retrieved easterly zonal flowof Mars southern solstice circulation is strongerand deeper than in dynamical models, although retrieved meridional winds (not shown) are similar.

  18. Detection of H2O2 in Mars (JCMT) Initial detection of Mars atmospheric H2O2,from JCMT during thefavorableMars opposition of late summer 2003. H2O2 is the most abundantspecies of the key catalytic HOx family, which effectively controls both the photochemical stability and trace chemical makeup of the global Marsatmosphere (Clancy et al. 2004). Clancy et al. (2004)Icarus168, 116.

  19. Atmosphere of Jupiter

  20. JUPITER H2--- <------------------------------NH3-------------------------------

  21. Calibration of spectral continuum to lunar flux (Pardo and Serabyn, ongoing work)

  22. Observation of low-frequency wing of NH3 line

  23. Cassini Composite Infrared Spectrometer (CIRS) at Jupiter

  24. [HF]<2.7×10-11 [HBr]<1.0×10-9 [HCl]<2.3×10-9 [HI]<7.6×10-9 Upper limits for hydrogen halides in Jupiter Fouchet et al. (2001). Icarus170, 237.

  25. Refit to data of Weisstein, E. W. and E. Serabyn (1996)Icarus123 23, 23. (a more detailed analysis by Mark Allen and students, Caltech, to come)

  26. SWAS Observations of H2O Vapor in Jupiter Bergin et al. 2000. Astrophys. J. 539, L147.

  27. Atmosphere of Saturn

  28. CH4 VMR = 3.9 ± 0.9 x 10-3 • CH4/H2 = 4.3± 1.0 x 10-3(for 88.1% H2) • C/H is 6 ± 2 times solar abundance • This is consistent with an accreting core of 10-12 MEarth (Mizuno 1980; Owen & Encrenaz 2003, 2005)

  29. Orton, Serabyn and Lee (2000)Icarus146, 48; (2001) Icarus149, 489. Reanalysis of data of Weissteinand Serabyn (1994) Icarus 109, 367. Weisstein and Serabyn (1996) Icarus 123, 23.

  30. SWAS Observations of H2O Vapor in Saturn Best fit: 2x nom H2O profile of Moses et al (2000) photochemical models Bergin et al. 2000. Astrophys. J. 539, L147.

  31. Atmosphere of Uranus

  32. from Griffin and Orton (1993) Icarus 105, 537.

  33. Atmosphere of Neptune

  34. Neptune’s Submm Spectrum from Griffin and Orton (1993) Icarus 105, 537.

  35. Observations of CO in NeptuneHesman et al. (2005) Submitted to Icarus. Gurwell (2005) In progress.

  36. Cassini CIRS Observations of Titan volume mixing ratios in stratosphere: CH4 : 1.6 ± 0.5 x 10-2 CO : 4.5 ± 1.5 x 10-5

  37. SMA Spectra of HC3N, HC15N, HCN in Titan, Gurwell

  38. SMA: HC15N Distribution in TitanGurwell et al. in progress

  39. Comet C/1999 H1 (Lee): SWAS ObservationsNeufeld et al. 2000. Astrophys. J. 539, L151. H2O line emission used to determine production rate vs time in the coma of Comet Lee; no evidence for periodicity

  40. ODIN Observations of Comet Ikeya-Zhang • 16O/18O ratio is nearly the same as for terrestrial oceans • also consistent with the ratio in Comet Halley

  41. ISO LWS observations of Ceres Spectrum is largely consistent with predictions for a standard thermophysical model

  42. From Redman et al. Astron. J. 116, 1478 BB=simple blackbody, eFF=1.0 HC=high conductor, rapid rotator LC=low conductor, slow rotator high conducting, rapid rotating model does best.

  43. ISO/LWS Observations: mineral / ice absorption …or just stray light from Jupiter? From Burgdorf et al. (2000) in “ISO Beyond the Peaks”, 9

  44. Issues: • Absolute Radiance Calibration • Spectroscopy

  45. Solar-System Objects as Flux Calibrators • Some Herschel instruments plan on using Uranus as a standard submillimeter flux calibrator, with Neptune and Mars as part of a calibration system. • How well-characterized are their fluxes? • How constant are their fluxes?

  46. URANUS STANDARD MODEL SPECTRUM (Griffin and Orton 1993 Icarus 105, 537) • Based on Voyager-1 IRIS spectra between 200 and 400 cm-1 • Model used to extrapolate spectrum • Temperature structure derived from 200 – 400 cm-1 spectrum • Collision-induced H2-H2, H2-He, H2-CH4 absorption - Molar fraction He = 0.155 ± 0.033 (Conrath et al. 1987 J. Geophys. Res. 92, 15003) - Molar fraction of CH4 = 0.02 ± 0.01 (Orton et al. 1996 Icarus67, 289, Lindal et al. 1987 J. Geophys. Res. 92, 14987) • Uncertainty of radiance ~2% between 50 and 500 cm-1 • Extrapolation to longer wavelengths is less certain.

  47. Uranus Variability?

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