Search Publications
A Spectral Dissection of the Ultraviolet Emissions of Capella
Ayres, Thomas R.
Phase-resolved observations of Capella (α Aurigae A: G5 III+G0 III) were conducted with the IUE in order to separate the spectrum of the core-helium-burning (CHeB) primary (Aa) from that of the fast-rotating, chromospherically active secondary (Ab). The ultraviolet emissions of the primary were compared to those of the four K0 giants of the Hyades…
X-Ray Spectrum and Variability of the Black Hole Candidate LMC X-3
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +4 more
LMC X-3 was observed on seven occasions in 1983-1984 with the EXOSAT satellite covering various orbital phases. No phase related variability was detected, while the X-ray flux increased gradually by ~ 30% in two weeks. Analysis of the short term variability in terms of autocorrelation reveals a minimum time scale of 600 s, with an rms amplitude of…
An Exceptional Change in the X-Ray Flux and Spectrum of the Seyfert 1 Galaxy E1615+061
Piro, L.; Perola, G. C.; Molteni, D. +1 more
The Seyfert 1 galaxy E1615 + 061 was found with the HEAO 1 A-2 experiment to possess a very soft X-ray spectrum, with an energy spectral index α >~ 2, much greater than typical (α ~ 0.6) for objects of the same class. The two EXOSAT observations described in this Letter show that in 1985 July this object was fainter than the HEAO 1 measurement …
Spectrophotometry and Chemical Composition of the Oxygen-poor Bipolar Nebula NGC 6164--5
Dufour, Reginald J.; Parker, Robert A. R.; Henize, Karl G.
The paper presents new ground-based and IUE spectrophotometry of several positions in NGC 6164-5 surrounding the Population I Of star HD 148937. Electron temperatures, densities, and abundances are derived for the various positions in the nebula using spectral line information. For all of the regions observed, Ne/H is depleted by an amount compara…
A White Dwarf Companion to the Main-Sequence Star 4 O 1 Orionis and the Binary Hypothesis for the Origin of Peculiar Red Giants
Johnson, Hollis R.; Ake, Thomas B.
In the course of an investigation with the IUE satellite of the ultraviolet spectra of peculiar red giants, the authors have discovered a white dwarf companion to the MS star 4 ο1Ori. They discuss the reductions performed for the ο1Ori IUE observations, and compare these with field white dwarfs to derive parameters of the whi…
The High-Resolution Soft X-Ray Spectrum of HZ 43. II. Bolometric X-Ray Flux, Effective Temperature, and Radius
Heise, J.; Bleeker, J. A. M.; Brinkman, A. C. +1 more
The authors present a reanalysis of the high-resolution soft X-ray spectrum of HZ 43, obtained with the 500 lines mm-1 transmission grating spectrometer on EXOSAT. They show here that the estimates of Te and log g from the shape of the X-ray spectrum depend critically on the code used to generate the model spectra, but that t…
The Outer Atmospheres of the Coolest M Giants: Ultraviolet Spectra of rho Persei, 2 Centauri, G Herculis, theta Apodis, and R Lyrae
Johnson, Hollis R.; Eaton, Joel A.
High-dispersion IUE spectra of five M giants (spectral type M4 - M7) are discussed. Most of the emission lines and stronger absorption lines are identified for ρ Per in the wavelength range λλ2320 - 3030. The chromospheric spectra of ρ Per, R Lyr, 2 Cen, and g Her are remarkably similar, both among themselves and with respect to stars of earlier s…
Observations of the Late Superhump in VW Hydri
Motch, C.; Beuermann, K.; van Paradijs, J. +2 more
This paper presents the results of simultaneous optical and near-IR photometry, optical fast spectroscopy, and Exosat X-ray observations of the dwarf nova VW Hyi, obtained simultaneously during three consecutive orbital cycles, approximately two days after the 1983 November superoutburst terminated. The optical data show clear evidence for a 'late…
Eight Years of Ultraviolet Spectra of the Variable BL Lacertae Object PKS 2155-305
Kondo, Y.; Urry, C. M.; Hackney, K. R. H. +1 more
The brightest known BL Lacertae object at ultraviolet wavelengths is PKS 2155-304, which was discovered as a result of its strong X-ray emission. Since 1979, 64 ultraviolet spectra of this object have been obtained with the International Ultraviolet Explorer (IUE) satellite. These have been analyzed in a consistent fashion using Gaussian extractio…
The C IV Doublet Ratio Intensity Effect in Symbiotic Stars
Altamore, A.; Kafatos, M.; Michalitsianos, A. G. +3 more
High-resolution UV spectra in the 1200-2000 wavelength range of the symbiotic variable R Aqr and its nebular jet were obtained in July 1987 with the IUE. The line profile structure of the C IV 1548, 1550 doublet in the jet indicates multicomponent velocity structure from an optically thin emitting gas. The C IV doublet profiles in the compact H II…