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Outflow in the nucleus of the Seyfert I galaxy NGC 3783.
Wamsteker, W.; Barr, P.
Averaged low-resolution IUE spectra of the Seyfert I galaxy NGC 3783 at two brightness levels are presented. The wavelength interval 1250-1400 A, which is essentially free of emission lines in active galaxies, contains two absorption lines at 1303 A and 1335 A. The line at 1303 A shows, in contrast to the line at 1335 A, considerable variations wi…
IUE spectroscopy, visible-band photometry and polarimetry of HD 47732(V641 Monocerotis).
Koch, R. H.; Hrivnak, B. J.; Bradstreeet, D. H. +3 more
Several high- and low-dispersion IUE spectra are described for the hot, massive close binary HD 47732. The stellar silicon lines do not show theoretically expected strength, the weakness being attributed to incipicent emission. A weak stellar wind is measurable with an expansion velocity of about 500 km/s. There is difficulty in fitting a model at…
On the planetary nebula NGC 3918.
Pena, M.; Torres-Peimbert, S.
We have obtained for this nebula high dispersion lUE spectra in the short and long wavelength ranges and with different exposure times. We have measured the emission line intensities and analyzed them. The density derived fiom different ions confirm that the nebula has no systematic density variations. The collisionally excited lines of [Mg V] 278…
Coordinated optical-EXOSAT-tenma observations of a burst from 2S1636-536
van Paradijs, J.; Pedersen, H.; Lewin, W. H. G. +6 more
During a coordinated observations of 2S1636-536 with EXOSAT, Tenma and the 1.4 metre Danish telescope at La Silla, a single burst was detected at all three observatories. The burst was bright with a peak flux of 6 × 10-8 ergs/cm 2 /s and rapid expansion of the blackbody radius. EXOSAT and Tenma agree closely in the values of…
Time-resolved UV spectroscopy of BE Ursae Majoris.
Hutchings, J. B.; Cowley, A. P.
Far-ultraviolet spectra have been obtained of the eclipsing, hot subdwarf binary, BE UMa, with phase coverage in the 2.3-day orbital period concentrated near minimum light. No clearly phase-related spectral changes were found, but the UV continuum appeared to be in a highly variable state, with changes of a factor of two occurring on a time scale …
The X-Ray and Optical Variability of the BLRG 3C390.3
Ward, M.; Barr, P.; Shafer, R.
We describe the optical emission line and continuum changes in 3C390.3. Also we present new EXOSAT results, and discuss their implication for determination of the X-ray spectrum — spectral index and absorbing column.
Ultraviolet spectra and chromospheres of R stars.
Johnson, H. R.; Eaton, J. A.; Obrien, G. T. +1 more
Long-wavelength IUE spectra of 13 normal R stars and two hydrogen-deficient R0 supergiants were obtained. Early R stars are noted to have line spectra and levels of flux in the ultraviolet characteristic of G5-K2 III stars, whereas late R stars were observed to have colors and line spectra similar to late K and M stars, but with greatly enhanced s…
X-Ray Variability of the Am-Herculis Star CW1103+254
Stella, L.; Beuermann, K.
The AM Her star CW1103+254 was observed with the low-energy and the medium-energy instruments of EXOSAT on 3 occasions for a total of 10.5 orbital cycles. Both, soft and hard X-rays from CW1103+254 were detected. We report preliminary results on the time variability of the X-ray emission on time scales from 1 minute to 1 month.
Discovery of an accretion shock cone in 22 Vulpeculae.
Parsons, S. B.; Ahmad, I. A.
A previous report that 22 Vul is a zeta Aurigae-type eclipsing binary is supported by the discovery of evidence for an accretion shock cone in 22 Vul similar to those found in zeta Aurigae and 32 Cygni. Such systems consist of a cool supergiant star primary and a hot dwarf secondary (G3 Ib-II and B9 in the case of 22 Vul) and undergo atmospheric e…
EXOSAT Observations of Flare Stars and Coronal Heating
Rodono, M.; Butler, C. J.
A program of observation of dMe stars is described that has been undertaken with EXOSAT as part of a collaboration of groups at Armagh, Catania, and JILA (University of Colorado) for multiband coverage of flare stars. The following conclusions were drawn: (1) The LE X-ray flux varies continuously over time scales of 20 seconds to hours with many s…