HST Imaging Observations of Jupiter's Hydrogen Corona

Jupiter is known to sustain a corona, with both an upper atmospheric temperature of 1000-2000 K and a small population of superthermal atomic hydrogen. Both of these phenomena require more energy than provided by the absorbed solar radiation. Understanding the physics of these energy inputs is important for understanding the energy balance of giant planets in general, and the conditions at giant extra-solar planets close to their parent stars. Toward this goal, imaging observations of Jupiter at UV wavelengths with the STIS instrument on the Hubble Space Telescope have been analyzed to study the latitude dependence of the H Ly alpha emission brightness using a method to separate the thermal and superthermal components of atomic hydrogen. The results are used to "map" the fraction of hot atoms versus latitude, showing that the hot atoms are concentrated at the magnetic dip equator rather than the rotational equator, consistent with past observations and confirming the hot atoms as the source of the "hydrogen bulge". The images, reduction technique, and results will be presented, along with a short discussion of the possible processes responsible for the hot hydrogen.