Astronomy and Astrophysics – Astronomy
Scientific paper
Sep 1996
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996dps....28.1905d&link_type=abstract
American Astronomical Society, DPS meeting #28, #19.05; Bulletin of the American Astronomical Society, Vol. 28, p.1128
Astronomy and Astrophysics
Astronomy
Scientific paper
The R(1) rotational line of HD at 56.23mu m has been detected for the first time on Saturn using the Long Wavelength Spectrometer (LWS) on the ESA Infrared Space Observatory (ISO) satellite. The measured spectrum has been compared with atmospheric models to determine the HD/H_2 abundance ratio. The best model fit to the measured spectrum was obtained with a D/H ratio of 2.3*E(-5) ; D/H values between 1.5*E(-5) and 3.5*E(-5) are however also compatible with the data. This result is intermediate between the saturnian value derived from ground-based observations of methane and its deuterated isotope, and the preliminary determination of the jovian D/H ratio measured by the mass spectrometer in the Galileo probe. The spectrum of Saturn over the full LWS range 43--197mu m was also measured and was compared with an atmospheric radiative-transfer model. Four results were obtained: first, the slope of the measured continuum within each detector passband is in good agreement with the model; second, absorption features due to ammonia and phosphine were unambiguously detected, and all detected features were attributed to these two molecules; third, the ammonia absorption features agree reasonably well with the nominal model based on Voyager IRIS measurements; and fourth, the phosphine absorption features disagree with the nominal model. Superior agreement with the measured spectrum was obtained using a modified PH_3 profile in which the tropospheric mixing ratio was increased to 7*E(-6) and the cutoff due to photodissociation was lowered to 300mbar. The preliminary Saturn measurements reported here will be repeated later in the ISO mission to improve the signal-to-noise ratio, and LWS measurements of HD on Jupiter, Uranus and Neptune will also be made.
Ade Peter A. R.
Burgdorf Martin
Calcutt Simon B.
Davis Gary R.
de Graauw Th.
No associations
LandOfFree
Early Results from the ISO Long Wavelength Spectrometer: Measurements of HD, PH_3 and NH_3 in Saturn does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Early Results from the ISO Long Wavelength Spectrometer: Measurements of HD, PH_3 and NH_3 in Saturn, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Early Results from the ISO Long Wavelength Spectrometer: Measurements of HD, PH_3 and NH_3 in Saturn will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1461815