Search Publications
Further constraints on the warm absorber in MR 2251-17.8 from GINGA and EXOSAT observations.
Mineo, T.; Stewart, G. C.
Analysis of a Ginga observation of MR 2251 - 17.8 is presented. The source is in a relatively low emission state, with a high absorbing column density. This result is consistent with the previous EXOSAT observations, where a strong correlation between the flux and the column density was detected. The Ginga spectrum and the entire EXOSAT spectral d…
A 4.86-h periodic modulation in the UV resonance lines of the cataclysmic variable V795 Herculis.
Prinja, Raman K.; Rosen, Simon R.
Low-resolution IUE spectroscopy of V795 Her secured in 1992 August is used to authenticate the presence of an approximately 4.86-h periodic variation in the mainly wind-formed Si IV 1400-A and C IV 1549-A resonance lines. The modulation is demonstrated to be coherent across a 3-yr time-span, and is discordant with the mooted orbital (optical spect…
A multi-frequency study of symbiotic stars - III. Simultaneous ultraviolet and optical observations of AX Persei.
Ivison, R. J.; Evans, A.; Bode, M. F. +2 more
The results of UV and optical monitoring of the classical symbiotic star AX Per are reported. The recent visual postoutburst light curve is used to estimate the size of the binary components in the AX Per system and to speculate on the cause of unusual ingress/egress profiles. A similar analysis using a phase plot of He II intensity is used to det…
Is the accretion disc of TT Ari hotter after a minimum ?
Pringle, J. E.; Tout, C. A.; La Dous, C.
Ultraviolet spectra of nova-like variables appear to be cooler than those of dwarf novae in outburst. This suggests that, once a steady-state accretion disc becomes established, it releases less of its energy thermally and more in other forms such as mass loss or magnetic flux. Here we use archival lUE data for the anti-dwarf nova TT Ari to show t…
Heavy mass loss from the symbiotic star AS 304.
Munari, Ulisse; Buson, Lucio M.
IUE, optical and infrared observations of the previously poorly studied symbiotic star AS 304 are discussed. The IUE low-resolution spectra are dominated by very strong P Cygni profiles of the resonant lines of N v, Si IV and C IV, indicating that the hot component of AS 304 is losing mass at a high rate via a fast wind. These P Cygni profiles mak…
Transfer function analysis of ultraviolet observations of NGC 5548.
Koen, Chris
A general linear transfer function relating an input series (UV continuum flux) to an output series (emission-line flux) is presented. The methodology for fitting the transfer function is briefly described. The autocorrelation structure of IUE observations of NGC 5548 in different spectral bands is investigated, and appropriate univariate autoregr…
IUE and HI observations of gas components towards HD 174632.
Davies, R. D.; Bates, B.; Kemp, S. N. +1 more
IUE spectra of gas components towards the nearby star HD 174632 are reported, together with 21-cm H I emission profiles obtained in the direction of the star and at several neighboring positions some 1 deg from the star. These new observations reveal a far more complex velocity structure of the interstellar gas than that reported through optical s…
The radial velocity and binarity of HD 153919 (4U 177A T The radial velocity and binarity of HD 153919 (4U 1700-37).
Stickland, D. J.; Lloyd, C.
New measurements of radial velocities from high-resolution lUE spectra of the massive X-ray binary HD 153919 give a velocity amplitude that is markedly smaller than that found in earlier studies, namely 5 km s-1, compared with previous values of around 20 km s-1. If such measurements relate to orbital motion, then the inferre…
The presence of fe VII and of low-ionization features in the UV spectra of central stars of planetary nebulae.
Tweedy, R. W.
The correlation between the presence of N I and Fe VII absorption lines in the spectra of central stars of planetary nebulae reported by Feibelman & Bruhweiler (1990) and Cheng et al. (1991) is refuted. Many spectra that they discuss are severely underexposed; moreover, 12 of them reveal no continuum whatsoever. These therefore cannot be used …