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Sungrazing Comets Discovered with the SOHO/LASCO Coronagraphs 1996-1998
Llebaria, A.; St. Cyr, O. C.; Lamy, P. +2 more
The Kreutz sungrazing family of comets is unique because of its small perihelion distance and because of the large number of known members of this family. SOHO/LASCO coronagraph observations beginning in 1996 have revealed an unprecedented number of Kreutz comets. These new coronagraph observations improve upon earlier observations because of a la…
Transition from Gaseous Compounds to Aerosols in Titan's Atmosphere
McKay, Christopher P.; Lebonnois, Sébastien; Bakes, E. L. O.
We investigate the chemical transition of simple molecules like C 2H 2 and HCN into aerosol particles in the context of Titan's atmosphere. Experiments that synthesize analogs (tholins) for these aerosols can help illuminate and constrain these polymerization mechanisms. Using information available from these experiments, we …
Dust Grains in the Comae and Tails of Sungrazing Comets: Modeling of Their Mineralogical and Morphological Properties
Kimura, Hiroshi; Mann, Ingrid; Jessberger, Elmar K. +1 more
Observations of sungrazing comets, all of which belong to the Kreutz family, provide the opportunity of studying the properties of dust in the comae and tails of the comets. On the basis of available information on cometary and interplanetary dust as well as observations of dust in the tails of sungrazers, we model dust in sungrazing comets as flu…
New Observational Results Concerning Jupiter's Great Red Spot
Achterberg, Richard K.; Flasar, F. Michael; Simon-Miller, Amy A. +4 more
The changing size and aspect ratio of the Great Red Spot from 1880 to 2000 are reviewed, indicating that the length of the system has decreased significantly over the last 100 years and continues to decrease at present at a rate of 0.19 degrees per year. Voyager IRIS maps of para hydrogen fraction and potential temperature over the system are pres…
Saturn's F Ring: Kinematics and Particle Sizes from Stellar Occultation Studies
Nicholson, P. D.; Bosh, A. S.; Olkin, C. B. +1 more
The occultation of GSC5249-01240 by Saturn's rings was observed in a spectrally resolved mode using the Faint Object Spectrograph on the Hubble Space Telescope. By combining these data with other occultation data, we have determined the inclination of the F ring to be 0.0065±0.0014 deg. Our inclined F ring orbit model explains an abrupt decrease i…
The Nucleus of Comet 22P/Kopff and Its Inner Coma
Jorda, L.; Lamy, P. L.; A'Hearn, M. F. +3 more
We report the detection of the nucleus of Comet 22P/Kopff with the Planetary Camera of the Hubble Space Telescope (HST) and with the Infrared Camera of the Infrared Space Observatory (ISOCAM). The HST observations were performed on 18 July 1996, 16 days after its perihelion passage of 2 July 1996, when it was at Rh=1.59 AU from the Sun …
HST Multicolor (255-1042 nm) Photometry of Saturn's Main Rings. I: Radial Profiles, Phase and Opening Angle Variations, and Regional Spectra
French, Richard G.; Dones, Luke; Cuzzi, Jeffrey N.
The main rings of Saturn were observed with the Planetary Camera of the WFPC2 instrument on the Hubble Space Telescope (HST) from September 1996 to December 2000 as the ring opening angle to Earth and Sun increased from 4° to 24°, with a spread of phase angles between 0.3° and 6° at each opening angle. The rings were routinely observed in the five…
A Study of Saturn's Ring Phase Curves from HST Observations
Poulet, F.; French, R. G.; Dones, L. +1 more
Solar phase curves between 0.3° and 6.0° and color ratios at wavelengths λ=0.336 µm and λ=0.555 µm for Saturn's rings are presented using recent Hubble Space Telescope observations. We test the hypothesis that the phase reddening of the rings is less due to collective properties of the ring particles than to the individual properties o…
Spatial and Compositional Constraints on Non-ice Components and H 2O on Pluto's Surface
Buie, M. W.; Grundy, W. M.
We present four new near-infrared spectra of Pluto, measured separately from its satellite Charon during four HST/NICMOS observations in 1998, timed to sample four evenly spaced longitudes on Pluto. Being free of contamination by telluric absorptions or by Charon light, the new data are particularly valuable for studies of Pluto's continuum absorp…
10 Hygiea: ISO Infrared Observations
Barucci, M. A.; Morris, P.; Crovisier, J. +10 more
Observations of emissivity features of 10 Hygiea have been made for the first time in the relatively unexplored thermal-infrared wavelength region with the ISO (Infrared Space Observatory) satellite. Spectrophotomer (PHT-S) and short wavelength spectrometer (SWS) spectra of 10 Hygiea, obtained at 5.8-11.6 and 7-45 µm, respectively, are prese…