Search Publications
Line variations in the ultra-violet spectrum of the Ap-Si star HD 25823.
Artru, M. -C.; Freire-Ferrero, R.
Spectral variations of the Ap-Si star HD 25823 are investigated in the UV range 1250-1900 A, from a set of five IUE images recorded during one rotational period. It is found that line intensities, as well as other wide absorption features, vary versus the phase (up to 20 percent) with different behaviors related to the absorbing elements. The equi…
An active hemisphere on II Peg.
Doyle, J. G.
IUE observations of the RS CVn star II Peg in the upper chromospheric and transition regions lines Mg II k, C IV, and He II in 1981, 1983 and 1985 shows evidence for increased activity at certain phases. The Mg II k line flux shows an above average value between phases 0.0 and 0.5. This is largely biased by the 1981 and 1983 data-sets, although th…
A relation between UV excess and the interstellar medium in elliptical galaxies ?
Sparks, W. B.; Collier Cameron, A.
We have obtained IUE spectra of the nuclear region of the dust-lane elliptical galaxy NGC 7196, with the intention of investigating a possible relationship between UV excess and the presence of a cool interstellar medium component in elliptical galaxies. This galaxy has a smooth, compact major-axis dust lane and no known nuclear activity. Excess U…
Massive Star-Formation Regions in the Magellanic Clouds
Thompson, I. B.; Hutchings, J. B.
We present optical and UV spectroscopy of stars from six compact, luminous groups or clusters in the SMC and LMC. The groups are characterized by high concentrations of nebulosity or starlight confined to areas smaller than 30" on a side, in which some stars can be resolved. The spectra and fluxes are used to derive luminosities and effective temp…
Empirical Continuum Modeling for IUE Low-Dispersion Spectra
Ayres, Thomas R.; Bennett, Jeffrey O.
The authors describe a numerical procedure for empirically determining a "continuum" level in low-dispersion spectra from the International Ultraviolet Explorer. They developed the technique for the automated fitting of SWP-LO (1150 Å - 2000 Å) spectra of stars of late spectral type, but it is more widely applicable.
Phase-resolved IUE Observations of AM Herculis System E1405-451
Nousek, J. A.; Takalo, L. O.
The authors report the first phase-resolved IUE observations of the AM Herculis system E1405-451. The spectra show bright emission lines from N V, C IV, and He II, whose centroids vary drastically during the 101.5 minute period. The radial velocities measured from the line centroids show a sinusoidal variation with a semi-amplitude of 300 km s
IUE--IRAS Studies of the Infrared Cirrus
Shull, J. Michael; van Steenberg, Michael E.
The authors have studied correlations of IRAS infrared cirrus fluxes with interstellar parameters toward 256 OB stars observed with IUE. The 60 and 100 µm fluxes correlate with N(H I), n, E(B - V), spectral type, vertical distance from the Galactic plane, and general UV illumination. No correlation was found with abundances of Si, Mn, Fe, S,…
Multiwavelength observations of the AM Herculis type system: MR Serpentis.
Schwarzenberg-Czerny, A.; Ward, M.; Jones, D. H. P. +4 more
The authors describe simultaneous ultaviolet and optical, as well as other observations of MR Ser during a high state. No substantial linear polarization was observed during an orbital cycle, but the circular polarization was high. The ultraviolet spectrum presents strong lines in emission of N V λ1240, Si IV λ1400, C IV λ1550 and He II λ1640, typ…
EXOSAT observations of the southern cluster of galaxies S 2008-569.
Piro, L.; Fusco-Femiano, R.
We present the X-ray spectrum of the source 3A 2008-568, associated with the southern cluster of galaxies S 2008-569, obtained with the ME detectors aboard the EXOSAT satellite. The flux was detected in a quadrant pointing in offset position to monitor the background during an observation of another target. An average intracluster gas temperature …
Rapid soft X-ray variability in a newly discovered active galaxy : EXO 1128+691.
Bedford, D. K.; Vilhu, O.; Petrov, P.
A previously unknown active galaxy has been discovered, and has been tentatively identified as a Seyfert type 1. 1t is possibly a member of the UMa I cluster. The X-ray emission differs from that for 'normal' Seyferts in that it is very soft and also shows rapid variability (~15 min to 2 hr). Assuming the galactic value N_H_~1.5x10^20^ cm^-2^ for …