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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…
Pluto's Non-isothermal Surface
Lellouch, E.; Crovisier, J.; Coustenis, A. +4 more
We report on repeated far-infrared photometric observations of the Pluto-Charon system conducted in 1997 with the Infrared Space Observatory (ISO). These observations have led to the first detection of the system at 150 and 200 µm and to the first clear detection of its thermal lightcurve at 60 µm (and more marginally at 100 µm).…
SOHO/SWAN Observations of the Structure and Evolution of the Hydrogen Lyman-α Coma of Comet Hale-Bopp (1995 O1)
Quemerais, E.; Bertaux, J. -L.; Combi, M. R. +2 more
The SWAN all-sky camera on the SOHO spacecraft observed the hydrogen Lyman-alpha coma of Comet Hale-Bopp (1995 O1) from January through May 1997. The observations covered heliocentric distances from 1.75 AU before perihelion to 1.29 AU after, showing the hydrogen coma to vary in brightness, shape, and orientation with the comet's orbital position.…
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…
NOTE: The Thermal Structure of Triton's Middle Atmosphere
Strobel, D. F.; Franz, O. G.; Elliot, J. L. +3 more
The atmospheric structure of Triton in the altitude range 25-150 km shows an unexpectedly steep thermal gradient of 0.26 K km -1 above 50 km altitude, with a nearly isothermal profile below. The upper part of the profile can be explained by downward conduction of heat deposited by magnetospheric electrons and solar UV. However, the atmo…
Latitudinal Profiles of the Jovian IR Emissions of H +3 at 4 µm with the NASA Infrared Telescope Facility: Energy Inputs and Thermal Balance
Achilleos, N.; Miller, S.; Prangé, R. +2 more
We present ground-based observations of the jovian ionospheric H +3 emission at 4 micrometers, using the CSHELL facility long-slit spectrograph at the NASA Infrared Telescope Facility (IRTF) in Hawaii. The data were obtained during four consecutive nights from July 13 to July 16, 1996. The 30-arcsec length slit of the spectro…