Search Publications
Rings and Satellites of Uranus: Colorful and Not So Dark
Karkoschka, Erich
Photometric properties of nine uranian satellites and four rings, based on six Hubble Space Telescope images taken in 1995, are presented. Derived albedos are consistent with previous data taken at the same phase angle of 1°, but inconsistent with most Voyager-based estimates extrapolated from observations at phase angles above 15°. The shape of p…
Atomic Sulfur in Cometary Comae Based on UV Spectra of the S ITriplet near 1814 Å
A'Hearn, Michael F.; Meier, Roland
We present a detailed study of the S I triplet emissions near 1814 Å in a variety of comets. Even in a moderately dense cometary coma the ground-state component (1807 Å) of the triplet turns out to be more or less optically deep. Therefore, any straightforward interpretation of the measured S I flux in terms of a gfactor and a column density is in…
Latitudinal Distribution of O 2on Ganymede: Observations with the Hubble Space Telescope
Spencer, John R.; Calvin, Wendy M.
To help constrain the spatial variation of oxygen on Jupiter's satellite Ganymede, and hence have more clues to its mode of production and stability, we have obtained spectral data from the Faint Object Spectrograph (FOS) for a single pole-to-pole latitudinal strip, along with several Wide Field Planetary Camera 2 (WFPC2) images in three narrow ba…
Latitudinal Variation of Aerosol Sizes Inferred from Titan's Shadow
Karkoschka, Erich; Lorenz, Ralph D.
We measured the location, size, and shape of Titan's shadow in five images taken with the Hubble Space Telescope in 1995. We inferred the altitude of Titan's optical limb at wavelengths of 337-954 nm to an accuracy of 15 km. At each wavelength, altitudes are constant north of -5° and also constant but lower south of -50° latitude, with a linear tr…
NOTE: an HST Search for Magnesium in the Lunar Atmosphere
Parker, Joel Wm.; Stern, S. Alan; Mendillo, Michael +5 more
In October 1996 we used the Hubble Space Telescope's Faint Object Spectrograph to make the first-ever mid-ultraviolet spectroscopic search for emissions from the lunar atmosphere. This spectrum revealed no emission lines, despite the fact that strong resonance emission transitions from the Al, Si, and Mg neutrals and from Mg+occur in th…
Temperatures and Altitudes of Jupiter's Ultraviolet Aurora Inferred from GHRS Observations with the Hubble Space Telescope
Fox, J. L.; Caldwell, John J.; Kim, Y. H.
We observed the jovian UV auroral regions with the Goddard high resolution spectrograph (GHRS) on board the Hubble Space Telescope (HST) on Apr. 29, May 2, and June 10, 1995. Observations of target areas were made in pairs in the two wavelength ranges 1257-1293 Å and 1587-1621 Å. Spectra in the long wavelength range are dominated by emissions of t…
Radiative Balance and Dynamics in the Stratosphere of Jupiter: Results from a Latitude-Dependent Aerosol Heating Model
Moreno, Fernando; Sedano, José
An updated dynamical model for the circulation in the jovian stratosphere has been developed. For computation of the heating and cooling rates in the stratosphere, required to obtain the radiative flux convergence, the model makes use of exponential-sum derived coefficients from laboratory and correlated-kdistributions from line listing data for t…
Simulation of the Morphology of the Jovian UV North Aurora Observed with the Hubble Space Telescope
Waite, J. H.; Grodent, D.; Gladstone, G. R. +2 more
A model simulating Earth views of UV auroral arcs and diffuse emissions in the Jovian north polar region is described. It assumes a Chapman profile of vertical brightness distribution and various horizontal structures. Simple geometric cases are described to illustrate the dependence on the altitude, atmospheric scale height, and central meridian …
ISOCAM Observations of the Comet P/Kopff Dust Trail
Reach, William T.; Boulanger, Francois; Sykes, Mark V. +3 more
We present the results of two scans through the dust trail of Comet P/Kopff made with ISOCAM on 26 March 1996. Positions behind the comet at mean anomalies of 0.5° and 1° less than the nucleus were imaged using the LW10 (IRAS Band 1, 12 µm) filter. The trail is clearly detected and appears to have varied since it was observed with the IRAS s…
Impact Mechanics and Frequency of SL9-Type Events on Jupiter
Ahrens, Thomas J.; Roulston, Mark S.
A semianalytic model for the breakup of fragments of Comet Shoemaker-Levy 9 upon entry into Jupiter's atmosphere is presented. The model assumes that the impacting fragments behave as bodies of viscous fluid and that the dominant process in their breakup is the growth of hydrodynamic instabilities. It is shown that the size of the smallest instabi…