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IUE Observations of Wolf-Rayet Binary Systems in the Small Magellanic Cloud
Moffat, Anthony F. J.; Koenigsberger, Gloria; Auer, Lawrence H.
The results of IUE observations of three SMC W-R binary systems at various orbital phases are presented. Selective atmospheric eclipse effects are evident in HD 5980 (WN 4 + O7 I:) and Sk 188 (W04 + O4 V), and are very weak or absent in Sk 108 (WN 3 + O6.5 I:). The difference in heavy-metal content between the SMC and Galactic objects is especiall…
Non-Planckian behaviour of burst spectra : dependence of the blackbodyradius on the duration of bursts.
van Paradijs, J.; Jansen, F.; Oosterbroek, T. +3 more
Exosat observations indicate a strong correlation between X-ray burst duration and the blackbody temperature measured at the moment when the flux has decayed to 10 percent of the Eddington flux. No correlation is observed between the persistent flux near the burst and this temperature. Burst spectra reveal deviations from a Planckian spectrum whic…
Deuterium content of the Venus atmosphere
Bertaux, J. -L.; Clarke, J. T.
THERE is no liquid water on Venus. The water vapour in its atmosphere would, if condensed, form a layer only 20 cm deep which means, in contrast to the 3-km-deep oceans that cover its sister planet Earth, that Venus is very dry indeed. It is not known with certainty whether Venus has lacked water since its formation, or if water once present has b…
Properties of plasma electrons in the magnetic pile-up region of comet Halley.
Anderson, K. A.; Rème, H.; Korth, A. +6 more
In the environment of comet P/Halley, a sharp transition, named the cometopause, was detected by the VEGA and GIOTTO spacecraft around 170000 km from the nucleus. In electron measurements, a clear discontinuity was detected 20% closer to the nucleus, than the cometopause as seen in the ion measurements. Significant changes in the electron distribu…
On the Signal-to-Noise Ratio in IUE High-Dispersion Spectra
Adelman, Saul J.; Leckrone, David S.
An observational and data reduction technique for fixed pattern noise (FPN) and random noise (RN) in fully extracted IUE high-dispersion spectra is described in detail, along with actual empirical values of signal-to-noise ratio (S/N) achieved. A co-addition procedure, involving SWP and LWR cameras observations of the same spectrum at different po…
The first decade of envelope formation of 59 Cygni in the far UV and optical regions. II.
Doazan, V.; Thomas, R. N.; Barylak, M. +3 more
Coordinated far-UV and optical observations of 59 Cygni are presented which, together with earlier results, describe the behavior of the entire atmosphere of the star during the first decade of formation and evolution of a new cool H-alpha emitting envelope. The data delineate an entire episode composed of a series of organized changes in the size…
IUE archive observations of dwarf nova WZ SGE during outburst.
Naylor, T.
Observations from the International Ultraviolet Explorer archive are used to show that during the 1978 outburst of the dwarf nova WZ Sge, its orbital light curve displayed dips, similar to those seen during the outbursts of other high-inclination dwarf novae. These dips are thought to be due to obscuration of the inner regions of the accretion dis…
Non-equilibrium ionisation in supernova remnants : the case of Tycho.
Haberl, F.; Brinkmann, W.; Smith, A. +1 more
A detailed numerical study of the X-ray emission of Tycho's supernova remnant which, at an age of about 430 years, has not yet reached its adiabatic phase of expansion. The carbon deflagration of a C + O white dwarf, which seems to be the most plausible model for type Ia supernova explosions, results in a highly nonsolar abundance distribution, wh…
The IUE-UV spectrum of the CP2 star HR 465.
Fuhrmann, K.
Consideration is given to eleven high resolution IUE spectra of the chemically peculiar star HR 465 obtained between 1979 and 1982. The spectra are compared to those of Pi Cet, Nu Cap, Vega, HD 101065, alpha exp 2 CVn, Kappa Cnc, HR 4072, and HR 7775. About 2500 lines are identified in the HR 465 spectra. Most of these lines belong to iron-peak el…
EXOSAT Observations of the Kepler Supernova Remnant
Arnaud, M.; Ballet, J.; Rocchia, R. +3 more
The medium-energy experiment on board Exosat was used to measure the X-ray spectrum of the Kepler supernova remnant over the range 1.5-10 keV. An Fe emission line was clearly resolved with an energy of about 6.5 keV and equivalent width of about 1.8 keV. This was superposed on a continuum with a temperature of 5.0(+3.8, -1.9) keV. The medium-energ…