Ultraviolet spectrometer observations of uranus

Area of Science:

• Planetary Science
• Atmospheric Physics
• Spectroscopy

Background:

• Uranus's upper atmosphere reaches 750 kelvins.
• Atomic and molecular hydrogen dominate Uranus's atmosphere.
• Methane and acetylene distributions are defined in lower atmospheric levels.

Purpose of the Study:

• Investigate the energy sources and characteristics of Uranus's atmospheric emissions.
• Determine the composition and structure of Uranus's upper atmosphere.
• Analyze the implications of atmospheric properties on Uranus's rings.

Main Methods:

• Solar and stellar occultations were used to gather atmospheric data.
• Ultraviolet spectroscopy analyzed emissions from the sunlit hemisphere.
• Electron energy distribution models were employed to understand excitation mechanisms.

Main Results:

• Electroglow emissions from atomic and molecular hydrogen were observed.
• Low-energy electrons (3-electron-volt Maxwellian distribution) are the likely excitation source.
• Dissociation of molecular hydrogen produces high-energy hydrogen atoms, contributing to a thermal corona.
• Auroral emissions were detected in the dark hemisphere.
• Acetylene volume mixing ratio estimated at 2 x 10(-7).
• Carbon emissions were detected.

Conclusions:

• Uranus's high atmospheric temperature and hydrogen corona influence ring particle orbital lifetimes and size distributions.
• Electroglow and auroral emissions provide insights into atmospheric energy transfer.
• Further research is needed to fully understand the energy sources driving these phenomena.