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Photochemistry of Saturn's Atmosphere. I. Hydrocarbon Chemistry and Comparisons with ISO Observations
Bézard, Bruno; Lellouch, Emmanuel; Moses, Julianne I. +3 more
To investigate the details of hydrocarbon photochemistry on Saturn, we have developed a one-dimensional diurnally averaged model that couples hydrocarbon and oxygen photochemistry, molecular and eddy diffusion, radiative transfer, and condensation. The model results are compared with observations from the Infrared Space Observatory (ISO) to place …
Photochemistry of Saturn's Atmosphere. II. Effects of an Influx of External Oxygen
Bézard, Bruno; Lellouch, Emmanuel; Moses, Julianne I. +3 more
We use a one-dimensional diurnally averaged model of photochemistry and diffusion in Saturn's stratosphere to investigate the influence of extraplanetary debris on atmospheric chemistry. In particular, we consider the effects of an influx of oxygen from micrometeoroid ablation or from ring-particle diffusion; the contribution from cometary impacts…
ISO-SWS Observations of Jupiter: Measurement of the Ammonia Tropospheric Profile and of the 15N/ 14N Isotopic Ratio
Drossart, Pierre; Bézard, Bruno; Lellouch, Emmanuel +4 more
We present the results of the Infrared Space Observatory Short Wavelength Spectrometer (ISO-SWS) observations of Jupiter related to ammonia. We focus on two spectral regions; the first one (the 10-µm region), ranging from 9.5 to 11.5 µm, probes atmospheric levels between 1 and 0.2 bar, while the second one (the 5-µm window), rang…
The Formation of Encke Meteoroids and Dust Trail
Reach, William T.; Sykes, Mark V.; Lien, David +1 more
We observed Comet 2P/Encke with the Infrared Space Observatory ISOCAM on July 14, 1997, from a particularly favorable viewing geometry above the comet's orbital plane and at a distance of 0.25 AU. A structured coma was observed, along with a long, straight dust trail. For the first time, we are able to observe the path of particles as they evolve …
Physical Properties of the Nucleus of Comet 2P/Encke
Fernández, Yanga R.; Weaver, Harold A.; A'Hearn, Michael F. +6 more
We report a new study of the nucleus of Comet 2P/Encke, which the CONTOUR spacecraft is scheduled to encounter in November 2003. During the comet's close approach to Earth in July 1997, we measured the mid-infrared thermal and optical scattered continua with data from the TIMMI instrument (imaging) at the ESO 3.6-m telescope (wavelength λ from 8 t…
Pluto's Non-isothermal Surface
Lellouch, E.; Crovisier, J.; Coustenis, A. +4 more
We report on repeated far-infrared photometric observations of the Pluto-Charon system conducted in 1997 with the Infrared Space Observatory (ISO). These observations have led to the first detection of the system at 150 and 200 µm and to the first clear detection of its thermal lightcurve at 60 µm (and more marginally at 100 µm).…
ISOPHOT Observations of Dust Disks around Main Sequence (Vega-Like) Stars
Walker, H. J.; Heinrichsen, I.
The photometer (ISOPHOT) on the Infrared Space Observatory (ISO) has proved to be invaluable for investigating the dust around main sequence stars (both prototypes and candidate Vega-like stars). The long wavelength camera (at 60 and 90 µm) has been used to map the area around the stars to establish whether the dust disk is extended. Low-res…
Vertical Distribution of PH 3 in Saturn from Observations of Its 1-0 and 3-2 Rotational Lines
Orton, Glenn S.; Serabyn, E.; Lee, Y. T.
Far-infrared Fourier-transform spectrometer measurements of the 1-0 and 3-2 PH 3 transitions in Saturn's disk near 267 and 800 GHz (8.9 and 26.7 cm -1), respectively, were analyzed simultaneously to derive a global mean profile for the PH 3 vertical mixing ratio between 100 and 600 mbar total pressure. The far-infr…
ISO Observations of Mars: An Estimate of the Water Vapor Vertical Distribution and the Surface Emissivity
de Graauw, Th.; Forget, F.; Lellouch, E. +9 more
Infrared spectra of Mars were taken with the two complementary spectrometers onboard the European Space Agency's Infrared Space Observatory (ISO), in both moderate- and high-resolution mode. From the strengths of the observed water lines we derived information about the vertical distribution of water vapor and on the emissivity of the dust/surface…
ISO LWS Observations of Mars—Detection of Rotational Modulation in the Far Infrared
de Graauw, Th.; Lellouch, E.; Burgdorf, M. +7 more
A series of far infrared (FIR) spectra of Mars between 43 and 196 µm was taken with the Long Wavelength Spectrometer (LWS) on board the European Space Agency's Infrared Space Observatory (ISO). Analysis of these medium-resolution data reveals a rotational modulation of the disk-averaged FIR brightness temperature. The observed variability of…