Principle Investigator: Laurence Trafton, University of Texas at Austin

Program Summary:

This is a proposal to use Gemini/GNIRS to search for and characterize the expected reversal of the long-term downtrend of the temperature of Uranus’ thermosphere, which has been in place since monitoring began 20 years ago, and which now extends half a season past the 2007 equinox, when global warming was minimal. We propose to monitor over the next three years the temperature of Uranus’ thermosphere at two effective depths, each probed independently by its near-IR H3+ and H2 spectra, in pursuit of the minimum for each. The epoch of each turnaround would determine the seasonal time constant of the thermosphere at each depth, thought to be controlled primarily by a non-radiative heat flux. The positioning of the excess heat source will be investigated by fitting radiative models into which a parametric heat source is inserted. Detecting only one minimum would still provide a significant constraint on the positioning.

Co-Investigators:

• Henrik Melin: University of Leicester
• Thomas Geballe: Gemini Observatory