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High-Velocity Ultraviolet Iron, Silicon, Oxygen, and Sulfur Absorption Features Associated with the Remnant of SN 1006
Fesen, Robert A.; Wu, Chi-Chao; Hamilton, Andrew J. S. +1 more
New low-dispersion IUE spectra of a faint sdOb star located in a direction near the center of the SN 1006 remnant are presented. The UV spectrum of the star exhibits several strong absorption features which are uncharacteristic of its optical sdOB star classification. The identification by Wu et al. (1983) of very broad absorption features at 1610…
A 23h EXOSAT observation of the X-ray pulsar 1E 2259+586 and the associated supernova remnant G 109.1-1.0
Coe, M. J.; Dennerl, K.; Hanson, C. G. +1 more
The X-ray pulsar, 1E 2259+586, and the associated supernova remnant, G 109.1-1.0 were observed with the EXOSAT on 1984 December 1/2. The pulse period at this epoch was 6.978720±0.000006(1σ) s, indicating that between 1981 and 1984 the pulsar was spinning down with an average secular rate of change of the spin period given by P/P = +[3.3±0.2]×10
Regular orbital variations in the ultraviolet resonance lines of YZ Cnc.
Verbunt, Frank; Drew, Janet E.
Observations with the International Ultraviolet Explorer of the dwarf nova YZ Cnc show regular orbital variations in the line profiles of the ultraviolet resonance lines. The P Cygni profile of the C IV λ1549 line changes drastically from absorption-dominated to emission-dominated, during the three observed orbits in each of two observation shifts…
Carbon and Nitrogen Lines in the Spectra of Wolf-Rayet Stars
Bhatia, A. K.; Underhill, A. B.
Predictions of 29 energy ratios involving emission lines of He II, C II, C III, C IV, N III, N IV, and N V are presented. Comparison of observed energy ratios with the predicted energy ratios shows that WC spectra can be understood in terms of solar composition, T* = 2.5 × 104K, 5×104 ≤ Te ≤ 105
Observations of three high-state eclipse egresses of Hercules X-1.
Fabian, A. C.; Tennant, A. F.; Day, C. S. R.
EXOSAT data from three high-state egresses of the pulsating X-ray binary Her X-1 are presented. Analysis of these data indicates that the extended atmosphere of the companion is the most likely explanation of the extent of the egresses. By fitting spectra taken from the egresses the authors find that the atmosphere has an exponential structure. If…
4 Draconis : a unique triple system containing an M3 giant and a cataclysmic binary.
Reimers, D.; Brown, A.; Griffin, R. F.
The M3 III giant 4 Dra has a UV bright companion discovered with IUE as a probable cataclysmic variable (CV). The authors determine the orbit of the M giant around the centre of gravity of the system that it forms with the cataclysmic binary and find P = 1703 d, e = 0.30, a1msin i = 82 Gm, and f(m) = 0.0076 M_sun;. They find that 4 Dra …
Mass Loss in a B2 IIIe Star: omega Orionis 1978--1984
Sonneborn, George; Grady, C. A.; Guinan, E. F. +4 more
Combination of long-term optical polarimetric, photometric, spectrometric, and ultraviolet spectral data have confirmed that all observed portions of ω Ori's outer atmosphere are variable on a variety of time scales. The spectacular polarization episodes are correlated with the presence of continuum flux and color changes but are not correlated wi…
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 …