Search Publications
Saturn's Zonal Winds at Cloud Level
Sada, Pedro V.; Sanchez-Lavega, Agustín.; Rojas, José F.
We present an analysis of new cloud motion measurements in Saturn's atmosphere from Voyager 1 and 2 images and define a nominal zonal wind velocity vs latitude profile for the cloud top level that can be used as reference for the upcoming Cassini mission. Improvements over previous studies include: (i) twice the number of wind vectors used, (ii) i…
Physical Properties of the Nucleus of Comet 2P/Encke
Fernández, Yanga R.; Weaver, Harold A.; A'Hearn, Michael F. +6 more
We report a new study of the nucleus of Comet 2P/Encke, which the CONTOUR spacecraft is scheduled to encounter in November 2003. During the comet's close approach to Earth in July 1997, we measured the mid-infrared thermal and optical scattered continua with data from the TIMMI instrument (imaging) at the ESO 3.6-m telescope (wavelength λ from 8 t…
Spatially Resolved Spectroscopy of Io's Pele Plume and SO 2 Atmosphere
McGrath, Melissa A.; Spencer, John R.; Belton, Michael J. S. +1 more
We report on the first successful, spatially resolved spectroscopic observations of Io's SO 2 atmosphere. Observations made with the Hubble Space Telescope Faint Object Spectrograph on 1 August 1996 using the 0.26 '' aperture have provided detections of SO 2 gas in absorption in three locations on the Io disk: the …
The Distribution and Physical State of H 2O on Charon
Buie, M. W.; Grundy, W. M.
We present new 1.4- to 2.5-µm geometric albedo spectra of Charon taken with HST/NICMOS in 1998. These new data provide global coverage of the surface with four spectra at evenly spaced longitudes. The surface of Charon is seen to be globally dominated by H 2O ice. The data indicate that the ice is in the crystalline phase at a tem…
The Surface of Titan from NICMOS Observations with the Hubble Space Telescope
Terrile, Richard J.; Smith, Bradford A.; Owen, Tobias C. +1 more
From diffraction-limited images produced by the near-IR camera NICMOS aboard the Hubble Space Telescope we derived maps of Titan's surface in the methane windows near 1.1, 1.6, and 2.0 µm. Each part of Titan's atmosphere and surface was imaged at least twice over a time period of 24 h to look for moving clouds. Despite careful analysis we fo…
Model Calculations for Io's Atmosphere at Eastern and Western Elongations
Smyth, William H.; Wong, Mau C.
Numerical calculations are performed for Io's sublimation atmosphere at eastern and western elongations using an improved version of the multispecies hydrodynamic model first developed by Wong and Johnson (1996). Subsolar SO 2 frost temperatures of 113 and 120 K are adopted to cover a range of plausible atmospheric abundances that are c…
Modeling the Dynamics of Cometary Fragments: Application to Comet C/1996 B2 Hyakutake
Jones, G. H.; Levasseur-Regourd, A. C.; Klinger, J. +1 more
A tridimensional model for the dynamics of cometary fragments is presented, using a direct integration of the vectorial sum of forces. This model is validated with a complete set of images of Comet C/1996 B2 Hyakutake, between March 22 and April 6, 1996, UT, by making the assumption that the bright condensations visible in the near-nucleus coma we…
Diagnostics of the Jovian Aurora Deduced from Ultraviolet Spectroscopy: Model and HST/GHRS Observations
Clarke, J. T.; Grodent, D.; Dols, V. +2 more
A model coupling an electron energy degradation code with a detailed synthetic spectrum of the H 2 Lyman and Werner band system is used to calculate the emerging auroral ultraviolet spectra from Jupiter's atmosphere excited by electrons with different initial energy distributions. The atmospheric model is adapted from the vertical P-T p…
Jupiter's Polar Regions in the Ultraviolet as Imaged by HST/WFPC2: Auroral-Aligned Features and Zonal Motions
West, Robert A.; Ballester, Gilda E.; Crisp, David +16 more
Jupiter's polar regions are examined using ultraviolet (UV, 120-320 nm) images obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 over the period of 1994-1997. These images probe the stratospheric aerosols at pressures of a few tens of millibars. We discovered a UV-darkened segment in the polar shading just equatorward of t…
Saturn's Ring-Plane Crossings of August and November 1995: A Model for the New F-Ring Objects
Nicholson, Philip D.; Sicardy, Bruno; Karkoschka, Erich +2 more
We analyze observations made in August and November 1995 during the Earth and Sun crossings of Saturn's ring plane, respectively. The August 1995 observations combine data taken with the Adonis adaptive optics system at the European Southern Observatory (ESO) and images from the Hubble Space Telescope (HST). The November 1995 data are based on HST…