D. Scott Davis

French National Centre for Scientific Research, Lutetia Parisorum, Île-de-France, France

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Publications (5)4.82 Total impact

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    S. Drapatz · Harold P. Larson · D. Scott Davis
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    ABSTRACT: A search for gaseous neutral CH4 was conducted in the coma of comet Halley on March 20, 1986 using a Fourier transform spectrometer on the Kuiper Airborne Observatory. In the field-of-view (24,000 km) the CH4 rotational temperature is equal to the kinetic temperature of the coma molecules due to collisions in most of the region and is frozen in at the outer edge. The spectrum of the nu3 band is due to fluorescence with the R(3) to R(5) lines being most suitable for Earth-based observations. Measured upper (3 delta) limits of 4 times 10 to the minus 19th power W/sqcm for these lines lead to a (7 delta) upper limit of 4 times 10 to the 28th power CH4 molecules per second. This value corresponds to 4% of the water vapor production rate at the time of observation.
    Preview · Article · Jan 1987
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    ABSTRACT: An infrared Fourier transform spectrometer on the Kuiper Airborne Observatory (KAO) was used to obtain high resolution spectra of the intense, solar-pumped infrared fluorescent emission in the (001 to 000) band of H2O near 2.6 microns. Differences between the observed H2O excitation and original expectations are discussed, and KAO water production rates are compared to those derived from International Ultraviolet Explorer observations. Possible future directions for high resolution IR spectroscopy of comets are discussed.
    Full-text · Article · Jan 1987
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    ABSTRACT: High-resolution observations of H2O in comet Halley are presented. The positions and widths of the H2O emission line profiles are indicative of the coma's velocity field characteristics. Spectral line shape changes are used to infer temporal variations in the kinematic properties of the outflow. The results suggest that H2O is released into the coma by way of multiple jets.
    Full-text · Article · Nov 1986
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    ABSTRACT: The atmospheric transmission window at 2.7 μm in Jupiter's atmosphere was observed at a spectral resolution of 0.1 cm−1 from the Kuiper Airborne Observatory. From analysis of the CH4 abundance (∼80 m-am) and the H2O abundance (<0.0125 cm-am) it was determined that the penetration depth of solar flux at 2.7 μm is near the base of the NH3 cloud layer. The upper limit to H2O at 2.7 μm and other recent results suggest that photolytic reactions in Jupiter's lower troposphere may not be as significant as was previously thought. The search for H2S in Jupiter's atmosphere yielded an upper limit of ∼0.1 cm-am. The corresponding limit to the elemental abundance ratio [S]/[H] was ∼1.7 × 10−8, about 10−3 times the solar value. Upon modeling the abundance and distribution of H2S in Jupiter's atmosphere it was concluded that, contrary to expectations, sulfur-bearing chromophores are not present in significant amounts in Jupiter's visible clouds. Rather, it appears that most of Jupiter's sulfur is locked up as NH4SH in a lower cloud layer. Alternatively, the global abundance of sulfur in Jupiter may be significantly depleted.
    No preview · Article · Dec 1984 · Icarus
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    ABSTRACT: A unique high resolving power near-infrared, astronomical Fourier spectrometer has been constructed foruse at both ground-based and airborne telescopes. Its capabilities include a limiting resolution of 0.01 cm(-1) and spectral coverage over the InSb detector sensitivity region (0.8-5.6 microm). The instrument is optimized for operation in environments inaccessible to other high-resolution Fourier spectrometers, namely, the Cassegrain focuses of conventional telescopes and the NASA Kuiper Airborne Observatory's 91-cm telescope. Details of the spectrometer are discussed, and various astronomical and laboratory spectra are presented.
    No preview · Article · Dec 1980 · Applied Optics

Publication Stats

91 Citations
4.82 Total Impact Points

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  • 1980
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France