Solar System Observations: Mars, Jupiter, Saturn, and Comet C/1999 H1 (Lee)
Abstract
The Submillimeter Wave Astronomy Satellite has obtained continuum and spectral line observations of several solar system objects during its first year of operation. The high spectral resolution provided by SWAS allows the pressure-broadened shape of molecular rotational lines to be accurately measured, which can be used to determine the global mean vertical structure of temperature and/or molecular abundance. Mars: Observations of Mars were obtained over several days near opposition in late April 1999. We report the detection of 13CO(5-4) and the ortho ground state H2O (110--101). The CO isotope has been used to constrain the vertical temperature profile, which is in excellent agreement with measurements made both with ground-based millimeter spectroscopy and Mars Global Surveyor. The water lineshape indicates that saturation vapor pressure dominates its distribution above 8 km. Jupiter and Saturn: We report that SWAS has detected ortho ground state H2O (110--101) emission from the upper atmospheres of both Jupiter and Saturn, confirming initial detections made with ISO. Our preliminary estimates find that the water must reside at or above about 5 millibar, well into the stratosphere. This suggests that the observed water is the product of ablation of icy grains bombarding the upper atmosphere. Comet C/1999 H1 (Lee): SWAS was used to detect the ground state H2O (110--101) emission from Comet Lee as it was approaching the sun (R 1.2 AU). We estimate that the water production rate at the time was 1.0x 1029 s-1. Over the 4.7 day period of observation, the water production rate showed no significant variation. The SWAS team gratefully acknowledges NASA contract NAS5-30702.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1999
- Bibcode:
- 1999AAS...195.6306G