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Discovery Of Mg-Rich Pyroxenes In Comet C/1995 O1 (Hale-Bopp): Pristine Grains Revealed At Perihelion
Woodward, Charles E.; Koike, Chiyoe; Wooden, Diane H. +2 more
The NASA Ames HIFOGS spectrometer observed comet C/1995 O1 (Hale-Bopp) at epochs including 96 Oct 7–14 UT (2.8 AU), 97 Feb 14–15 UT (1.2 AU), 97 Apr 11 UT (0.93 AU), and 97 Jun 22, 25 UT (1.7 AU). The HIFOGS 7.5–13.5 µm spectrophotometry (R = 360 - 180) of the silicate feature at 2.8 AU is identical in shape to the ISO SWS spectra of comet H…
NICMOS/HST Post-Perihelion Images of Comet Hale-Bopp in Outburst
Spinrad, H.; Schneider, G.; McCarthy, D. +5 more
Near-infrared images of comet Hale-Bopp (C/1995 O1) were obtained from NICMOS/HST on UT August 27–28, 1997, when the comet emerged from the 50 degree solar elongation limit at 2.99 AU from Earth. Diffraction-limited images were obtained with camera 2 filters centered at 1.87, 1.90, 2.04 and 2.22 µm with ∼0.2″ resolution (0.076″/pixel; 165 km…
Isophot Observations Of Comet Hale-Bopp
Lemke, D.; Leinert, Ch.; Heinrichsen, I. +11 more
Comet Hale-Bopp has been observed five times with ISOPHOT, the photometer on board the Infrared Space Observatory (ISO), four times before its perihelion passage at heliocentric distances of 4.92, 4.58, 2.93 and 2.81 AU, and at 3.91 AU postperihelion. Each time, multi-filter photometry covering the range between 3.6–175 µm with eight to ten …
Unusual Comets (?) as Observed from the Hubble Space Telescope
Weaver, Harold A.; Meech, Karen J.
In separate projects, the Hubble Space Telescope has been used to assess the nature of 3 unusual objects: Chiron, Pholus and P/Shoemaker-Levy 9. This paper will compare these objects and discuss how the unique capabilities of the HST may be used to address the issue of cometary activity in each. Chiron, which has exhibited obvious cometary charact…
On the Importance of Dust in Cometary Nuclei
Keller, H. U.; Kührt, E. K.
The icy conglomerate model introduced by Whipple more than 40 years ago has been widely accepted in cometary science because it is able to describe numerous cometary phenomena. In this model comets are described as a conglomerate of ices and dust where the ices represent the major component. However, some recent observations seem to favour dust ri…
Interpretation of HMC Images by a Combined Thermal and Gasdynamic Model
Kührt, E.; Keller, H. U.; Knollenberg, J.
Images of comet Halley's nucleus taken by the HMC camera during the GIOT-TO encounter in 1986 show that a major part of the total dust production is localized in a few active areas which are the sources of gas-dust jets. The global dust distribution in the inner coma is dominated by two main jets roughly directed to the sun. A combination of a 1D …
High Resolution Imaging of Pluto and Charon with the Faint Object Camera of the Hubble Space Telescope
Albrecht, R.
Images of the Pluto-Charon system were obtained with the Faint Object Camera (FOC) of the Hubble Space Telescope (HST) with the aim of determination of radii, fluxes, and albedos. The resolution of the already diffraction limited images was further improved by image restoration, yielding indications of surface albedo distributions which are qualit…