Search Publications

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…

Bl-Lacertae Objects from the EXOSAT High Galactic Latitude Survey - Constraints on the Logn-Logs and on the Cosmological Evolution

Tagliaferri, G.; Beuermann, K.; Branduardi-Raymont, G. +8 more

Using a sample of 11 X-ray selected BL Lacertae objects extracted from the EXOSAT High Galactic Latitude Survey we derive the LogN-LogS relation of BL Lacs and we compare it with the results obtained with other X-ray surveys. All EXOSAT BL Lacs are characterized by featureless optical spectra and have been detected in the radio band. Excellent agr…

Evidence for the field line reconnection process in the particle and magnetic field measurements obtained during the Giotto-Halley encounter.

Neubauer, F. M.; Korth, A.; Daly, P. +5 more

Measurements of low (E = 250 - 1000 eV) and high (E = 60 to >300 keV) energy particles as well as the magnetic field obtained during the Giotto-Halley encounter on 13/14 March 1986 are used to study the field line merging process. Strong changes in the pitch angle distribution of energetic ions are observed simultaneously. The observations are …

Detection of a Strong Excess Noise Component in the Low State of 4U 1705-44

Hasinger, G.; Truemper, J.; Langmeier, A.

The timing analysis of four Exosat observations of the bright Galactic burst source 4U 1705-44 is presented. A correlation is found between the aperiodic noise components and the spectral variability. 4U 1705-44 shows in its low-intensity state a strong variability of the X-ray flux in the frequency range 1-64 Hz, corresponding to an rms modulatio…

A study of ultraviolet spectra of dzeta Aurigae/VV Cephei systems. XI. 22 Vulpeculae : IUE observations of its extended chromosphere and wind with spatial resolution.

Reimers, D.; Schroeder, K. -P.

A set of 18 high resolution IUE spectra of chromospheric-eclipse phases of 22 Vulpeculae are analyzed by means of growth curves. A density model is presented and the upper limit of the electron density is determined. Si II UV mult. 2 wind resonance lines at several phases are modeled with a two-dimensional transfer code. It is found that although …

Discovery of a Cool Expanding Shell at -1200 Kilometers per Second around V471 Tauri

Sion, Edward M.; Bruhweiler, Fred C.; Mullan, Dermott +1 more

High-resolution IUE spectra of V471 Tauri reveal the presence of a very-high-velocity cool expanding gas in the line of sight to the binary system with an expansion velocity of -1200 km/s. The summed strength of the coadded absorption is 125 mA + or - 25 mA, with FWHM = 30 km/s. It is suggested that the observed absorption may be related to the na…

Spectroscopic binary orbits from ultraviolet radial velocities. Paper 5: 29 (UW) Canis Majoris

Stickland, D. J.