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Cometary dust trails I. Survey
Sykes, Mark V.; Walker, Russell G.
Cometary dust trails were first observed by the Infrared Astronomical Satellite and consist of large refractory particles ejected from short-period comets at low velocities. Consequently, they tend to be found near the orbital paths of their parent bodies, their long and narrow appearance reminescent of airplane contrails. An examination of the en…
0.7- to 23-µm photometric observations of P/Halley 1986 III and six recent bright comets
Gehrz, R. D.; Ney, E. P.
We report 0.7- to 23-µm observations of P/Halley 1986 III and six other recent bright comets. P/Halley was measured on 47 occasions between 1985 December 12 UT and 1986 May 6 UT, several times within hours of the perihelion passage on 1986 February 9 UT. Our data show that the strength of the 10-µm silicate emission feature and the tem…
Hubble space telescope observations of the 1990 equatorial disturbance on Saturn: Zonal winds and central Meridian albedos
Beebe, R. F.; Westphal, J. A.; Barnet, C. D. +1 more
Two sets of Hubble Space Telescope (HST) data, obtained in August 1990 and November 1990, are compared with Voyager 1 and 2 data acquired in 1980 and 1981. A rare disturbance developed in the equatorial region of Saturn in late September 1990. Due to the large equatorial wind shear, this disturbance generated inhomogeneous bright cloud structures …
Titan: Evidence for seasonal change—A comparison of Hubble space telescope and voyager images
Weaver, H. A.; Tomasko, M. G.; Caldwell, John +7 more
Images of Titan were obtained by the Hubble Space Telescope (HST) on 26 August 1990. Comparison with Voyager 1 and Voyager 2 images obtained 10 and 9 years earlier shows that the seasonal hemispheric brightness asymmetry has reversed near 440 and 550 nm wavelengths, with the northern hemisphere now being brighter. An additional, noisy HST image at…
The onset and growth of the 1990 equatorial disturbance on Saturn
Beebe, R. F.; Barnet, C.; Murrell, A. S. +1 more
The development of cloud structures at low Saturnian latitudes in September 1990 can be divided into three phases: the onset and expansion of the initial disturbance (popularly known as the Great White Spot), the eastward and westward expansion of the bright cloud, and the eventual formation of wave-like structures encircling the equator. The thre…
The origin of complex organic ions in the coma of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
Heavy ion mass spectra were obtained in the inner coma of Comet Halley by the Giotto-PICCA instrument. Outside the cometary ionopause, where ≳2000 K ion temperatures limited the effective mass resolution to 3 amu, the spectra exhibit a series of distinct mass groups that are separated by a constant ≈ 15 amu and extend to at least 120 amu. We show …
Hubble space telescope observations of the 1990 equatorial disturbance on Saturn: Images, albedos, and limb darkening
Ingersoll, Andrew P.; Baum, William A.; Westphal, James A. +4 more
In September 1990 a major equatorial eruption on Saturn produced a disturbance that spread in longitude until it completely girdled the planet. We report here on 150 images recorded in six passbands with the Wide Field/Planetary Camera (WF/PC) aboard the Hubble Space Telescope (HST) on 17 and 18 November 1990. For comparison, we used HST-WF/PC obs…
IUE observations of H Lyman-α in comet P/Giacobini-Zinner
Feldman, Paul D.; Combi, Michael R.
Comet P/Giacobini-Zinner (1985 XIII) was observed during the flyby of the International Cometary Explorer (ICE) satellite and during the 3 preceding months by the International Ultraviolet Explorer (IUE) satellite. Models for the hydrogen abundance and spatial distribution, which were previously used to reproduce the observed spatial distribution …
Inner coma imaging of Comet Levy (1990c) with the Hubble space telescope
Feldman, P. D.; A'Hearn, M. F.; Weaver, H. A. +5 more
Comet Levy (1990c) was observed with the Hubble Space Telescope (HST) on UT 27 September 1990 when both the heliocentric and geocentric distances were ∼1 AU. Two sets of images of the comet were taken 6.5 hr apart with the Wide-Field Camera (WFC) through a broadband red filter that was selected to isolate continuum emission peaking sharply at the …
Pluto's extended atmosphere: An escape model and initial observations
Stern, S. A.; Clarke, John T.; Trafton, Laurence M.
We have calculated the rates of production and hydrodynamic outflow of atomic hydrogen resulting from the photodissociation of methane in the upper atmosphere of Pluto. Under the present near-perihelion conditions this yields an extended cloud of H around Pluto which is likely to be the most easily observable signature of Pluto's extended atmosphe…