A Solar Occultation By Titan Observed By Cassini/Vims

Details A Solar Occultation By Titan Observed By Cassini/Vims A Solar Occultation By Titan Observed By Cassini/Vims

Sep 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006dps....38.2201b&link_type=abstract

American Astronomical Society, DPS meeting #38, #22.01; Bulletin of the American Astronomical Society, Vol. 38, p.519

Astronomy and Astrophysics

Astronomy

Scientific paper

We present results of a solar occultation by Titan's southern atmosphere, observed on January 15th 2006 by the Cassini Visual and Infrared Mapping Spectrometer (VIMS), at distances ranging from 5,000 to 10,000 km. This occultation was mainly caused by absorption from gaseous spectral bands and hazes. When refraction began to be significant - below 100 km altitude - more than 90% of the initial solar flux was actually absorbed. The infrared spectra (from 0.85 to 5.1 µm) acquired at successive altitudes show several absorption bands of CH4 (1.7 µm, 2.3 µm, 3.2 µm), CO (4.7 µm) and CO2 (4.3 µm). Radiative transfer model with a uniform abundance profile of 1.6 % of CH4 provides a good fit of CH4 bands, especially at 2.3 µm. Agreement between the data and model deteriorates as altitudes below 350 km are probed, corresponding to the haze layer. Large absorption and/or scattering probably explains this discrepancy. The 4.7 µm CO absorption band is observed below 1 mbar ( 190 km), and is consistent with a uniform abundance of 30 to 60 ppm for CO. These values are also consistent with previous VIMS and CIRS measurements (K.H. Baines et al., 2006 & F.M. Flasar et al., 2005). As for CH4, haze absorption and scattering should explain the disagreement between the data and the models under 70 km altitude. Possible effects of vertical variations of CO abundance will also be presented. The haze tangential optical depth is described with a simple model, based on ground-based Titan occultations. When scaled with wavelength, this model works well to fit the continuum part of VIMS spectrum. Finally, a large absorption feature is seen at 3.4 µm (blended with 3.2 µm CH4 band) for altitudes lower than 450 km, and is possibly caused by C-H bounds of solid haze particles.

Affiliated with

Also associated with

No associations

Rating

A Solar Occultation By Titan Observed By Cassini/Vims 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 A Solar Occultation By Titan Observed By Cassini/Vims, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Solar Occultation By Titan Observed By Cassini/Vims will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-999353