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Solar Flux Variability and the Lifetimes of Cometary H 2O and OH
Feldman, P. D.; Festou, M. C.; Budzien, S. A.
The far and extreme ultraviolet (FUV/EUV) solar flux determines the photodestruction rates of H2O and OH in cometary comae and affects their spatial density distributions. Between the minimum and maximum of the solar activity cycle, the solar flux varies by as much as a factor of 2-3 at some FUV and EUV wavelengths. From recent cross se…
Sulfur Dioxide in the Atmosphere of Venus. II. Modeling Results
Esposito, L. W.; Barth, C. A.; McClintock, W. E. +1 more
We have analyzed the results from the UV sounding rocket observations of Venus made on 15 September 1988 and 29 March 1991 which obtained high-resolution spectra of Venus clouds from 199 to 230 nm. The albedo of Venus in this wavelength range is dominated by absorption features of sulfur dioxide and sulfur monoxide. We estimate that the mixing rat…
Ultraviolet Spectra and Geometric Albedos of 45 Asteroids
Buratti, B. J.; Roettger, E. E.
Spectral reflectances and geometric albedos between 2300 and 3250 Å are determined for 45 asteroids from data acquired by the International Ultraviolet Explorer satellite. The geometric albedos are consistently tow, ranging from ∼0.02 for C-type asteroids to ∼0.08 for M-type asteroids. An exception is the single E-type asteroid (44 Nysa) with a ge…
The Nature of the Source of CO in Comet P/Halley
Samarasinha, Nalin H.; Belton, Michael J. S.
We show by numerical simulations that the CO distribution in the coma of Comet P/Halley as measured by neutral gas mass spectrometer aboard Giotto spacecraft (P. Eberhardt et al., 1987, Astron, Astrophys, 187, 481-484) can be explained by an extended jet source originating from vent 1 in the rotational model of M. J. S. Belton et al. (1991, Icarus…
The Ultraviolet Spectrum of Triton from HST: First Results
Stern, S. Alan; Trafton, Laurence M.
We report on the first Hubble Space Telescope (HST) spectra of Neptune's largest satellite, Triton. The spectra were taken on 16-17 May 1992 by the HST Faint Object Spectrograph. They span the region 2220-3278 Å. This overlaps IUE spectra of Triton we obtained, 2700-3100 Å, and penetrates the region from 2220 to 2550 A for the first time. The deri…