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Hard X-ray spectrum of 4U 1907+09.
Rao, A. R.; Chitnis, V. R.; Agrawal, P. C. +1 more
We have studied the binary X-ray source 4U 1907+09 in the energy range 20-100 keV, using a xenon-filled multilayer proportional counter telescope flown with balloons from Hyderabad in 1985 and 1991. Results of these observations are reported. The source was detected above 20 keV at a significance level of 13 sigma in 1985 and marginally detected i…
Solar wind thermal electrons from 1.15 to 5.34 AU: Ulysses observations
Balogh, A.; McComas, D. J.; Goldstein, B. E. +3 more
Using unique 3-d velocity space measurements by the Ulysses solar wind plasma experiment from 1.15 to 5.34 AU, we assess the radial gradient in thermal electron temperature. Until 3.8 AU, the gradient was steeper than previously reported but flatter than adiabatic; after 3.8 AU the gradient flattened. Trends in the observed electron distribution s…
MHD modeling applied to Giotto encounter with comet P/Grigg-Skjellerup
Neubauer, Fritz M.; Wegmann, R.; Schmidt, H. U.
First from a one-dimensional MHD model we derive estimates for position and shape of the bow shock applicable for arbitrary magnetosonic Mach numbers >1 in the solar wind. This generalization is important in the case of the Giotto encounter with P/Grigg-Skjellerup with the unusual interplanetary magnetic field (IMF) of 18 nT. We compare three-d…
Rotational modulation and flares on RS Canum Venaticorum and BY Draconis stars. XVII. UV spectroscopy and optical photometry of AU Microscopii in 1986.
Doyle, J. G.; Quin, D. A.; Butler, C. J. +2 more
We present IUE spectroscopy and optical photometry of the active late type star AU Mic. The UV spectroscopy allow us to measure the chromospheric and transition region line fluxes. No detectable variations attributable to rotational modulation were evident in either the chromospheric lines or optical bands. We have produced an emission measure cur…
Imaging the Bipolar Nebula around HM Sagittae
Paresce, Francesco; Hack, Warren J.
Hubble Space Telescope Faint Object Camera UV images are presented for HM Sge showing a bipolar optical nebula similar to that in R Aquarii and RX Puppis. The nebula extends to a distance of 0.174" with a P.A. of 135 degrees inside a faint halo extending to a radius of 0.28". A kinematic distance to HM Sge based on positions of features in the neb…
Water Production Rates in Comet P/Halley from IUE Observations of HI Lyman-β
Feldman, Paul D.; Combi, Michael R.
During the 1985-1986 apparition of Comet P/Halley, the International Ultraviolet Explorer (IUE) satellite observed the comet using both the long-wavelength and short-wavelength spectrographs. The combination of a spherical radiative transfer model and the hybrid gas-dynamic/Monte Carlo model for hydrogen coma, which had been used to analyze H Lyma…
Signal-to-Noise Ratios in IUE Low-Dispersion Spectra. II. Photometrically-Corrected Images
Ayres, Thomas R.
The character of detector noise is explored in photometrically-corrected images from the shortwavelength and longwavelength prime intensified vidicon cameras of the International Ultraviolet Explorer. A protocol is proposed for deriving realistic "noise models"--crucial to the application of Optimal extraction algorithms like that of Kinney, Bohli…
Optical and ultraviolet observations of the star LkHα 264.
Collier Cameron, A.; Gameiro, J. F.; Lagor, M. T. V. +1 more
We present new ultraviolet and optical data for the classical T Tauri star LkH-alpha 264. The most important features in the UV spectrum are identified and their fluxes are measured. These fluxes are then compared to the corresponding values in the sun and in other T Tauri stars. Our time series of high-resolution spectra for the regions of the H-…
Relativistic electron flux anisotropies in the duskside Jovian magnetosphere: a test for source location and escape mechanism
Simpson, J. A.; McKibben, R. B.; Zhang, Ming
Results of anisotropy analyses of >∼ 3 MeV electron flux data obtained by the high-energy telescope of the COSPIN experiment on Ulysses are presented for the period from day 40 to day 45 of 1992, when the spacecraft was outbound from Jupiter in the duskside high-latitude magnetosphere and magnetosheath. At small L-shells or minimum magnetic lat…
The radio and optical structure of 3C 66B.
Sparks, W. B.; Macchetto, F.; Miley, G. K. +1 more
We report new, high-resolution radio observations of the jet in 3C 66B. The filaments in the optical jet seen in the HST image of Macchetto et al. are also visible in the radio image. The structure of the radio jet is complex and filamentary beyond the brightest knot. It is consistent with the HST image, which appears to consist of a central kinke…