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The Ultraviolet Spectrum of eta Carinae
Cassatella, Angelo; Viotti, Roberto; Rossi, Lucio +2 more
An atlas of the high-resolution UV spectrum of Eta Car from 1200 to 1974 A and from 2200 to 3230 A is presented, based on IUE observations made between 1978 and 1980. The fluxes and equivalent widths of the emission and absorption features, and the stellar continuum in line-free regions are presented. The profiles displayed by the most intense emi…
A Soft X-Ray Survey of Hot White Dwarfs with EXOSAT
Heise, J.; Paerels, F. B. S.
Broadband multicolor soft X-ray photometry of 34 hot white dwarfs is presented, obtained with the Low Energy Imaging Telescopes on Exosat. By combining the soft X-ray fluxes with measurements of the stellar parameters in the UV and optical bands, photospheric He abundances for 16 of the 21 hot DA white dwarfs are derived. Supplemented by five star…
The giant haloes of NGC 6543 and 6826.
Walsh, J. R.; Clegg, R. E. S.; Middlemass, D.
Long-slit spectra at several positions on the large faint haloes of NGC 6543 and 6826 were obtained using IPC spectrograph and CCD detectors. It is shown that the halo emission is thermal in origin, and that the forbidden O III electron temperature is higher in each halo than in its central nebula. Halo electron temperature values of 14,700 K for …
The velocity distributions of cometary protons picked up by the solar wind
Balsiger, H.; Neubauer, F. M.; Fuselier, S. A. +3 more
Velocity space distributions of picked up cometary protons were measured by the ion mass spectrometer on the Giotto spacecraft upstream of the Halley bow shock. Large pitch angle anisotropies were observed at all distances >1.2×106 km from the comet. As expected, pitch angle diffusion was much more rapid than energy diffusion. When t…
Emission-Line Variability of Fairall 9: Determination of the Size of the Broad-Line Region and the Direction of Gas Motion
Koratkar, Anuradha P.; Gaskell, C. Martin
A cross-correlation analysis has been performed on 118 IUE spectra of Fairall 9 available from 1978 to January 1987 to determine the size of the broad-line region and the average direction of gas motion. Analysis of the line flux shows that the C IV λ1549 emitting region is 124 +/- 39 light days from the central source and the Mg II λ2800 emitting…
Rotational modulation and flares on RS Canum Venaticorum and BY Draconis stars. XI. Ultraviolet spectral images of AR Lacertae in September 1985.
Linsky, J. L.; Walter, F. M.; Neff, J. E. +1 more
High-resolution IUE SWP and LWP spectra of the bright eclipsing RS CVn system AR Lac, obtained during 40 h of continuous observations on September 18-19, 1985, are compiled and used to derive chromosphere images. The data and results are presented graphically and discussed in detail. The K 0 IV star is found to have a globally brighter trailing he…
The luminous quasar HS 1700+6416 and the shape of the "big bump" below 500 A.
Clavel, J.; Reimers, D.; Wamsteker, W. +5 more
In the course of the Hamburg quasar survey a bright (V = 16.1) high redshift (z = 2.72) quasar has been discovered. Follow-up optical high (0.4 A) and low (6 A) resolution spectrophotometry together with IUE observations are presented. With a luminosity at λ_rest_ = 1450 A, L_1450_ = 6 x 10^32^ erg s^-1^ Hz^-1^, HS1700+6416 is the second most lumi…
The flux and spectral variability of NGC 6814 as observed with EXOSAT.
Branduardi-Raymont, G.; Mittaz, J. P. D.
We present five EXOSAT observations of the Seyfert galaxy NGC 6814 which were carried out over the period 1983 September to 1985 October at intervals of a few months to a year. Over these time-scales the soft X-ray (0.02-2.5 keV) flux of NGC 6814 varies by large factors, decreasing by over and order of magnitude in the first 9 months; this is foun…
EXOSAT observations of the X-ray burst source 4U 1608-52.
van Paradijs, J.; Lewin, W. H. G.; Tan, J. +2 more
The results of an analysis of two Exosat observations (July 1984, May 1986) of the highly variable X-ray burst source 4U 1608-52 are presented. During both observations the persistent X-ray flux was low (quiescence), and the persistent X-ray spectrum could be well fitted with a power-law model, with approximately the same index, but a somewhat dif…
UV Fluorescence of Molecular Hydrogen and Red Dust Emission in the Gamma Cassiopeiae Nebulae IC 63
Bohlin, Ralph C.; Witt, Adolf N.; Stecher, Theodore P. +1 more
Resonant fluorescence of molecular hydrogen has been observed in the reflection nebula IC 63 with the IUE satellite. Both the noncoherent resonant scattering and the dissociative continuum are shown to agree well with molecular theory. Extended red emission is also found in this nebula and may be physically related to the dissociation of H2.