Search Publications
Ultraviolet variations in the spectrum of the visible central star of Abell 35.
Jasniewicz, G.; Lapierre, G.; Monier, R.
We report on simultaneous IUE and photometric observations carried out in March 1992 of the G8IV star BD-22 3467 located at the centre of the planetary nebula Abell 35. The main feature of the IUE low resolution spectra is a strong Mg II emission, which is common in fairly close binaries. Meanwhile no variations of the hot companion were detected …
A preliminary list of stars from TYCHO observations
Bastian, U.; van Leeuwen, F.; Petersen, C. +6 more
The final Tycho Catalog will be a major source of astrometric standard stars when it will be published, in 1997. While the Tycho positions with their full accuracy will only be available at the end of the data reduction, it is already possible to derive a preliminary list of about one million stars from the Tycho Input Catalogue (TIC) which have a…
Photometric calibration of the international Ultraviolet Explorer (IUE) for high resolution spectra.
Vogel, M.; Gonzalez-Riestra, R.; Cassatella, A. +2 more
We present and discuss the high resolution absolute calibration for the SWP, LWP and LWR cameras on board IUE. The calibration was implemented in routine processing on 27 December, 1987 at VILSPA and on 30 August, 1990 at GSFC. The calibration is applicable to high resolution spectra processed with the 'new' version of the IUE spectral image proce…
Simultaneous observations of γ-ray bursts with Phebus/Granat and ULYSSES GRB.
Hurley, K.; Sunyaev, R.; Sommer, M. +9 more
We compare the characteristics of 35 gamma-ray bursts (GRBs) detected simultaneously by Phebus aboard Granat and the Ulysses GRB experiment. Phebus observes a medium to high energy range (100 keV - 100 MeV), while the Ulysses GRB detector is sensitive to lower energy photons (25-150 keV). Comparison of the peak counts recorded by these two instrum…
A statistical study of IUE spectra of dwarf novae. I. Quiescence.
Deng, Shi-Bing; Zhang, Zhong-Yong; Chen, Jian-Sheng
Based on more than 1200 IUE spectra of dwarf novae, we investigate the statistical properties of these systems, concerning the correlation of the spectra with parameters of the binary system. The results provide a way of testing the current accretion disk model and of understanding the physical conditions in dwarf novae. The present paper is restr…
Observational constraints on the inter-binary stellar flare hypothesis for the gamma-ray bursts
Rao, A. R.; Vahia, M. N.
The Gamma Ray Observatory/Burst and Transient Source Experiment (GRO/BATSE) results on the Gamma Ray Bursts (GRBs) have given an internally consistent set of observations of about 260 GRBs which have been released for analysis by the BATSE team. Using this database we investigate our earlier suggestion (Vahia and Rao, 1988) that GRBs are inter-bin…
The corona of the G-type giant HR 2554: discovery of co-existing, very different temperature regimes.
Schroeder, K. -P.; Huensch, M.
We present direct observational evidence for two different co-existing coronal temperature regimes in the ζ Aur-type binary HR 2554 (G7II + A1V). ROSAT observations reveal the presence of plasma at temperatures around 10^6.7^K, typical of coronal plasma found in giants, while IUE observations, taken during egress from eclipse, show circumstellar (…
The ultraviolet variations of the δ Scuti stars 44 Tauri and 71 Tauri.
Monier, R.; Kreidl, T. J.
We report on low resolution phase resolved ultraviolet spectrophotometry of the δ Scuti stars, 44 Tau (F2 IV-V) and 71 Tau (F0V) at different phases of their pulsation cycles performed with the International Ultraviolet Explorer. For 44 Tau, the amplitude of the flux variations increases towards shorter wavelengths from about 13% around 3000A, to …
Observations by ULYSSES of a pure electron event and its associated type III radio emission of 15 December 1990
Chaizy, P.; Pick, M.; Forsyth, R. +8 more
We describe an interplanetary electron event associated with a type III radio burst observed by Ulysses at 1.37 AU. This event was observed when the spacecraft crossed a region of strong compression between a fast and a slow solar wind stream, characterized by a relatively high density and a complex behaviour of the plasma density, magnetic field …
Multiwavelength observations of RV Tauri stars. IV. SX Centauri.
Evans, A.; Shenton, M.; Albinson, J. S. +6 more
We present ultraviolet, optical and infrared observations of the RV Tauri star SX Cen. From a fit of model atmospheres to the data we conclude that Z/Zsun_=0.033, that SX Cen has an extended atmosphere, and that the spectral types implied by the ultraviolet data close to deep minimum are consistent with those implied from optical spectr…