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The optical and UV spectrum of the Seyfert type 2 galaxy NGC 3393.
Prieto, M. A.; Wamsteker, W.; Diaz, A. I.
The combined UV and optical spectrum of the Seyfert type 2 galaxy NGC 3393 is presented and analyzed together with published IR and IRAS data. The conditions in the narrow line gas strongly suggest that the high ionization material is in a zone of higher density (N_e_=10^5^ cm^-3^) while the low ionization material is at N_e_=10^3^ cm^-3^. No evid…
New constraints on neutron star models of gamma-ray bursts. I. EXOSATobservations of two gamma-ray burst error boxes.
Hurley, K.; Boer, M.; Niel, M. +13 more
Two EXOSAT observations of gamma-ray burst error boxes and their possibly associated optical transients are discussed. No point source was detected in either box. A comparison with Einstein data (Pizzichini et al., 1986) is made for one of them (November 19, 1978). The data are interpreted in the framework of neutron star models for gamma-ray burs…
Rotational modulation and flares on RS CVn and BY DRA systems. VIII. Simultaneous EXOSAT and H alpha observations of a flare on the dMe star GL 644 AB (Wolf 630) on 24/25 August 1985.
Tagliaferri, G.; de La Reza, R.; White, N. E. +5 more
A large flare was detected simultaneously in X-rays and H-alpha on the visual binary Gl 644 AB at about 00:15 UT on August 25, 1985. The flare was detected with both the low (0.05-2 keV) and medium energy (2-7 keV) experiments onboard Exosat, with the flare rise time being similar in both the low and medium energy ranges, although in the low energ…
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
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 …
High-resolution spectroscopy of central stars of planetary nebulae : LSS 1362.
Werner, K.; Heber, U.; Drilling, J. S.
High resolution spectra of the hot sdO star LSS 1362, a central star of a planetary nebula, are analyzed by means of model atmosphere techniques. Improved NLTE model atmospheres based on the newly developed 'accelerated lambda iteration' method are used. The very high effective temperature (100000 K) derived previously from the UV energy distribut…
The recurrence behaviour of X-ray bursts from 4U/MXB 1735-44.
van Paradijs, J.; Lewin, W. H. G.; Sztajno, M. +2 more
During about 80 h of uninterrupted observations of the X-ray burst source 4 U/MXB 1735-44, made in August 1985 with Exosat, five bursts were observed. The bursts occur at irregular intervals, ranging between 30 min and 36 h. The burst sizes do not scale with the intervals preceding the bursts; in particular the energy in a burst which occurred aft…
IUE observations of high galactic latitude F supergiants HD 161796 and HD 187885.
Pottasch, S. R.; Wamsteker, W.; Parthasarathy, M.
Low resolution (6 A) IUE ultraviolet spectra of the high galactic latitude F supergiants HD 161796 (F3 Ib) and HD 187885 (F2-3I) are analyzed. The UV spectrum (1250 A to 3250 A) of HD 161796 shows no excess UV flux attributable to a hot degenerate companion. From the UV spectrum the temperature is found to be 6300 K. There is no evidence for signi…
Far-ultraviolet and X-ray emission of the long period RS CVn star sigma Geminorum.
Linsky, J. L.; Kjeldseth-Moe, O.; Westergaard, N. J. +6 more
The new UV and X-ray observations of σ Gem support the theory that large active regions associated with starspots are responsible for the enhanced line emission commonly seen in RS CVn systems. The rotational modulation of the UV line fluxes increases with temperature of the line-forming region. The X-ray emission from the stellar corona, on the o…
Variations of the ultraviolet spectrum of 3C 273 : 9 years of IUE data.
Wamsteker, W.; Ulrich, M. -H.; Courvoisier, T. J. -L.
The quasar 3C 273 has been observed with the IUE satellite in the range 1200-3000 A every two weeks from 29 November 1986 to 18 February 1987, with additional observations in May 1986 and 1 June and 17 July 1987. These recent observations are analyzed together with the archived IUE spectra from 1978 to 1985. The flux at 1275 A undergoes variations…