Search Publications
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…
ISOPHOT Observations of Dust Disks around Main Sequence (Vega-Like) Stars
Walker, H. J.; Heinrichsen, I.
The photometer (ISOPHOT) on the Infrared Space Observatory (ISO) has proved to be invaluable for investigating the dust around main sequence stars (both prototypes and candidate Vega-like stars). The long wavelength camera (at 60 and 90 µm) has been used to map the area around the stars to establish whether the dust disk is extended. Low-res…
Vertical Distribution of PH 3 in Saturn from Observations of Its 1-0 and 3-2 Rotational Lines
Orton, Glenn S.; Serabyn, E.; Lee, Y. T.
Far-infrared Fourier-transform spectrometer measurements of the 1-0 and 3-2 PH 3 transitions in Saturn's disk near 267 and 800 GHz (8.9 and 26.7 cm -1), respectively, were analyzed simultaneously to derive a global mean profile for the PH 3 vertical mixing ratio between 100 and 600 mbar total pressure. The far-infr…
Heliospheric Latitude Variations of Properties of Cometary Plasma Tails: A Test of the Ulysses Comet Watch Paradigm
Brandt, John C.; Snow, Martin
Images of comets de Vico in 1995, Hyakutake in 1996, and Hale-Bopp in 1997 taken by observers in the Ulysses Comet Watch clearly show plasma tail properties reflecting the demarcation of the solar wind into distinct equatorial and polar regions with the boundary determined by the maximum extent of the heliospheric current sheet (HCS). Generally, (…