Search Publications
Analysis of nebulosity in the planetary nebula NGC 40.
Seaton, M. J.; Clegg, R. E. S.; Torres-Peimbert, S. +1 more
Optical and IUE spectra of a bright region of nebulosity in the planetary nebula NGC 40 have been combined for an analysis of the physical conditions and abundances in the nebula. Resulting abundances are typical of planetary nebulae and indicate that the nebulosity does not share the extreme abundances of the Wolf-Rayet WC8 central star. The cont…
The symbiotic star H1-36.
Allen, D. A.
The high-excitation emission-line star H1-36 is investigated using optical and infrared spectrophotometry. It is established that H1-36 may be classified as a symbiotic star due to the presence of a variable M giant. The observations are analyzed in terms of the usual binary model for symbiotic stars in which an unseen star is heated by accretion …
IUE observations of W UMa-type stars.
Vilhu, O.; Rucinski, S. M.
IUE (International Ultraviolet Explorer) low-resolution SWP images of the contract binaries 44i Boo, VW Cep, W UMa, V566 Oph, AW UMa, V502 Oph, Epsilon CrA, RR Cen and the very close non-contact binary ER Vul have been studied. The results are compared with other UV and soft X-ray data and it is found that the stellar activity within this group is…
The ultraviolet variability of NGC 3783.
Willis, A. J.; Wilson, R.; Barr, P.
The results of three years of monitoring the spectral variability of the type 1 Seyfert galaxy NGC 3783 with IUE spacecraft instrumentation are reported. Techniques for fitting power laws to the observed wavebands are described, noting the monitoring was carried out in the 1150-3150 A region. The continuum was found to vary by a factor of ten over…
Phase-dependent UV spectra of UX Ursae Majoris.
Jameson, R. F.; King, A. R.; Sherrington, M. R. +1 more
The authors report phase-dependent UV spectra of UX UMa. The behaviour of the continuum during eclipse is as expected for an optically thick accretion disc. The authors confirm that the C IV λ1549 emission line is not eclipsed, and show that several other lines undergo partial or total eclipses. This behaviour is shown to be consistent with simple…
The Seyfert 1 galaxy NGC 4593 - I. Variability of the UV spectrum andphysical conditions in the broad line emitting region.
Penston, M. V.; Clavel, J.; Bergeron, J. +2 more
Results obtained for UV observations of NGC 4593 are reported. The observations were carried out at two epochs using the low resolution spectrograph and the large apertures of the IUE satellite. The data reduction is presented. The properties of the UV continuum as well as its variability are investigated, discussing the selection of continuum win…
Further ultraviolet observations of interstellar gas associated with the supernova remnant S 147.
Gondhalekar, P. M.; Phillips, A. P.
The IUE satellite was used to obtain high-resolution ultraviolet observations of the star HD 37318 (B0.5Ve) which lies behind the supernova remnant S 147. High-velocity interstellar absorption lines (>VLSR< ≅ + 80 km s-1) were detected which originate in gas associated with the remnant. These lines have been analysed to…
HZ Her: the nature and origin of the emission lines.
Howarth, I. D.; Wilson, B.
The line spectrum of HZ Her/Her X-1 is investigated in highand low-dispersion IUE spectroscopy. It is noted that while velocity considerations discredit the classical sites of mission, which are the primary star's X-ray heated photosphere, accretion stream, and disk, they support an origin in discrete blobs of material orbiting at the rim of the a…
IUE observations of X-ray selected Seyfert galaxies.
Willis, A. J.; Wilson, R.; Barr, P.
Results are presented for 1150-3150 A spectrophotometry of six type I Seyfert galaxies - NGC 5548, Markarian 79, Markarian 279, Markarian 506, Markarian 376, and 3C 390.3. It is found that the continuous flux distribution can be represented by a single power law in four of these objects, with spectral indices between + 0.2 and - 3.1, while NGC 554…
The conspicuous absence of normal graphite grains in the Small Magellanic Cloud.
Bromage, G. E.; Nandy, K.
The simplest dust model that accurately predicts the normal Galactic interstellar extinction, also fits the normal SMC curve derived from visible and IUE observations. Only one parameter value is different: the usual graphite contribution is at least a factor of 7 weaker in the SMC. Some possible explanations are discussed.