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De Bergh, C.

Publications and source records attributed to De Bergh, C..

11 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Water in the deep atmosphere of Venus from high-resolution spectra of the night side

High-resolution, near-infrared (1.09 to 2.5 micrometers) spectra of the night side of Venus have been obtained in 1990 and 1991 using the Fourier Transform Spectrometer at the 3.6-m Canada-France-Hawaii telescope. Absorptions due to H2O were detected in spectral windows near 2.3, 1.74, and 1.18 micrometers. Our analysis of these absorptions constrains the abundance of water vapor in three different altitude ranges located between the clouds and the surface: 30-40 km, 15-25 km and 0-15 km. A constant water vapor mixing ratio of 30 +/- 15 ppm below the clouds can fit the observations. These values are consistent with recent near-infrared studies of the night side of Venus at lower spectral resolution. The atmosphere of Venus appears to be dryer than originally suggested by the in-situ measurements made by the Pioneer Venus and Venera mass-spectrometers and gas-chromatographs.

De Bergh, C.↗
NASA NTRS1994

Dark matter in the outer solar system

There are now a large number of small bodies in the outer solar system that are known to be covered with dark material. Attempts to identify that material have been thwarted by the absence of discrete absorption features in the reflection spectra of these planetesimals. An absorption at 2.2 micrometers that appeared to be present in several objects has not been confirmed by new observations. Three absorptions in the spectrum of the unusually red planetesimal 5145 Pholus are well-established, but their identity remains a mystery.

Owen, T.↗
NASA NTRS1994

Four micron high-resolution spectra of Jupiter in the North Equatorial Belt: H3(+) emissions and the C-12/C-13 ratio

Spectra of the North Equatorial Belt of Jupiter were obtained in March 1992 at an unapodized resolution of 0.1/cm between 2450 and 2600/cm with the Fourier Transform Spectrometer at the 3.6 m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea. Several emissions from the nu(sub 2) band of H3(+) were detected. The excitation temperature derived from the relative intensities of these emissions averaged over a wide range of longitudes is 800 +/- 100 K, and the H3(+) column density is 1.56(sup +1.0)(sub -0.5) x 10(exp 11)/sq. cm. In addition, several strong absorption features due to (13)CH4 were observed. A comparison between (12)CH4 and (13)CH4 absorptions allowed us to obtain a new measurement of the C-12/C-13 ratio. We found that this ratio, estimated for the first time in this spectral range, is 89 (+/- 25), in agreement with the terrestrial value.

Marten, A.↗
NASA NTRS1990

Monodeuterated methane in the outer solar system. IV - Its detection and abundance on Neptune

The 3nu2 band of CH3D was detected in the spectrum of Neptune near 1.6 micron recorded at a spectral resolution of 4/cm with the Cassegrain Fourier Transportation Spectrometer at the 3.6 m Canada-France-Hawaii Telescope CFHT) on Mauna Kea. The analysis of this spectrum, using spectral synthesis techniques, yielded a CH3D/CH4 ratio of about 0.0006, which corresponds to a global D/H ratio for Neptune of about 0.00012, if CH3D is in isotopic fractionation equilibrium with HD. This value is about an order of magnitude larger than an earlier estimate by Orton et al. (1987) based on deconvolution measurements of unresolved molecular emission in the 8-10-micron region. Comparison of this new determination with previous studies of CH3D in the outer solar system shows that, as in the case of Uranus, the D/H on Neptune is strongly enhanced over that found on Jupiter and Saturn and is comparable to the D/H in methane on Titan and in terrestrial methane and water.

De Bergh, C.↗
NASA NTRS1988

Monodeuterated methane in the outer solar system. III - Its abundance of Titan

The 3nv2 band of CH3D has been detected in spectra of Titan recorded at 1.6 microns with the Fourier transform spectrometer at the 4 m telescope of the Kitt Peak National Observatory. A value of the CH3D/Ch4 mixing ratio is obtained from a comparison between the observed Titan spectra and synthetic spectra. This value is about 2 times higher than the value measured on Uranus (de Bergh et al. 1981, 1986) and about 6 times higher than on Jupiter and on Saturn (Courtin et al. 1984; de Bergh et al.). The value found on Titan for D/H in methane is comparable to the D/H ratio measured in terrestrial H2O.

De Bergh, C.↗
NASA NTRS1986

Monodeuterated methane in the outer solar system. II - Its detection on Uranus at 1.6 microns

The 3 nu 2 band of CH3D has been detected in the spectrum of Uranus recorded with the Fourier Transform Spectrometer at the 4 m Mayall telescope of Kitt Peak National Observatory. A scattering-model atmosphere and spectral synthesis techniques are used to derive a bulk CH3D/CH4 mixing ratio of 3.6 + 3.6 or - 2.8 x 10 to the -4th from these observations that suggests a deuterium enhancement in methane relative to that observed on Jupiter and Saturn.

De Bergh, C.↗
NASA NTRS1986

Deuterium in the outer solar system - Evidence for two distinct reservoirs

A series of determinations of the CH3D/CH4 ratio in the atmospheres of Saturn, Titan, and Uranus has been completed. These results, coupled with the work of other investigators, suggest that the solar system contains at least two distinctly different primordial reservoirs of deuterium: that contained in gaseous hydrogen and that contained in the volatiles which have been maintained at low temperatures or isolated from hydrogen; for example, trapped in cold, solid material. Both of these reservoirs were established before the formation of the solar system.

Owen, T.↗
NASA NTRS1983

Monodeuterated methane in the outer solar system. I Spectroscopic analysis of the bands at 1.55 and 1.95 microns

The analysis of the near-infrared spectrum of monodeuterated methane (CH3D) near 6400/cm and 5100/cm is presented. Three new parallel bands which have locally perturbed upper states connecting with the ground state are identified, and approximate rotational constants are derived. The band centered near 6425/cm and the 9613 A band previously analyzed by Lutz, Danehy, and Ramsay (1978) are found to form an apparent vibrational progression with the nu2 fundamental at 2200/cm, and vibrational assignments of 3nu2 and 5nu2, respectively, are proposed. Detailed comparison of the rotational constants of the states involved is shown to support these assignments.

Lutz, B. L.↗
NASA NTRS1983

Titan - Discovery of carbon monoxide in its atmosphere

The 3-0 rotation-vibration band of carbon monoxide was identified in the near-infrared spectrum of Titan. A preliminary mixing ratio of CO/N2 = 0.00006 was determined. This result supports the probable detection of CO by Samuelson et al and strengthens possible analogies between the atmosphere of Titan and conditions on the primitive earth. Previously announced in STAR as N83-14039

Lutz, B. L.↗
NASA NTRS1981

On the possible detection of CH3D on Titan and Uranus

The possible spectral detection of monodeuterated methane, CH3D, in the atmospheres of Titan and Uranus is reported. The detection was made on the basis of the identification of a new band centered near 6425 per cm in laboratory spectra of CH3D, which could possibly account for the strength of the methane absorption near 6400 per cm observed in the interferometric spectra of Titan and Uranus of Fink and Larson (1979). On the basis of measurements of the CH3D/CH4 natural abundance ratio and the estimated band strength of the 6425 per cm band, it is concluded that approximately 15% of the observed methane absorption is due to CH3D, rather than a pure temperature effect in CH4.

Lutz, B. L.↗