Search Publications
UV spectroscopy of Z Chamaeleontis - I. Time-dependent dips in superoutburst.
Sonneborn, G.; Charles, P. A.; Hassall, B. J. M. +2 more
Extensive IUE observations of the dwarf nova Z Cha during the 1987 April superoutburst and IUE-Exosat observations during the 1985 July superoutburst are presented. The UV light curve shows two dips when folded on the orbital period. One dip, at orbital phase 0.8 becomes shallower as the superoutburst progresses and can be associated with decreasi…
A search for the 2omega-omega frequency in the X-ray light curves of intermediate polars.
Hellier, Coel
Wynn and King (1992) have shown that diskless accretion gives rise to modulations at either the omega-Omega or 2omega-Omega frequencies in the X-ray light curves of intermediate polars. However, the EXOSAT archive shows no sign of a 2omega-Omega modulation in any of the systems observed. An omega-Omega modulation larger than half the spin-pulse am…
IUE observations of the shells of RR PIC and GK Per.
Evans, A.; Bode, M. F.; Duerbeck, H. W. +1 more
We present UV observations of the resolved shells of the old novae RR Pic (1925) and GK Per (1901). On the assumption that the RR Pic nebula is photoionized by the ultraviolet continuum emitted by the stellar remnant, we conclude that nitrogen is overabundant relative to solar in both the 'equatorial ring' and 'polar blob' regions; there are steep…
Variability in the UV resonance lines of the cataclysmic variable V795 Herculis (PG 1711+336).
Drew, Janet E.; Prinja, Raman K.; Rosen, Simon R.
Variability in the UV resonance lines from the cataclysmic variable V795 Her is investigated on the basis of a total of 28 IUE SWP low-resolution spectra. Significant line profile fluctuations are evident in the C IV 1549 and Si IV 1400 doublets on time-scales down to less than about 30 min. There is little or no evidence for changes in N V 1240. …
UV spectroscopy of the X-ray binary AC 211 (= 4U 2127+11) in M 15.
Raymond, J. C.; Charles, P. A.; Hassall, B. J. M. +2 more
Time-resolved International Ultraviolet Explorer observations are presented of the low-mass X-ray binary AC211/4U2127 + 11 in the globular cluster M15 (NGC 7078). The spectra show He II 1640-A emission, the flux of which is modulated on the 8.5-hr orbital period of AC211. This modulation and the ratio of He II 1640 A to He II 4686 A and C IV 1550 …
The interrelation of UV and optical activity diagnostics in HK Lacertae.
Houdebine, E. R.; Butler, C. J.; Olah, K. +3 more
The study examines and compares optical photometric and UV (IUE) spectroscopic data on the active RS CVn star HK Lac gathered in the years 1979, 1980, and 1987. The photometry is modeled by representations of 'starspots' and, in general, it is found that the UV emission lines are stronger at times of spot maximum. The variable interstellar absorpt…
The hot subdwarf in the eclipsing binary HD 185510.
Simon, Theodore; Jeffery, C. S.; Evans, T. L.
High-resolution spectroscopic measurements of radial velocity are employed to characterize the eclipsing binary HD 185510 in terms of masses and evolutionary status. The IUE is used to obtain the radial velocities which indicate a large mass ratio Mp/Ms of 7.45 +/- 0.15, and Teff is given at 25,000 +/- 1000 K based on Ly alpha and UV spectrophotom…
A new kind of oscillation in the persistent emission of the Rapid Burster.
Stella, Luigi; Lewin, Walter H. G.; van Paradijs, Jan +3 more
We present a study of a new kind of oscillation found in the persistent emission after some type II bursts from the Rapid Burster observed during 1985 August with EXOSAT. All 95 bursts observed were longer than 30 s. Ten of them were followed by these oscillations. The frequency of the oscillations ranged from 39 to 56 mHz. A period decrease (by 3…
Pulse phase-resolved X-ray spectroscopy of the transient high-mass X-ray binary V 0332+53.
Coe, M. J.; Unger, S. J.; Lehto, H. J. +1 more
An analysis is conducted of Exosat observations of the transient binary X-ray pulsar V 0332 + 53 during a series of flares, which yielded simultaneous high energy and time resolutions. The results obtained are interpreted in terms of a system in which the line-of-sight from the earth is not close to the magnetic axis of the neutron star, and in wh…
Double star CCD astrometry and photometry
Irwin, M. J.; Argue, A. N.; Bunclark, P. S. +3 more
Results are presented for angular separation, position angle and V and R photometry for 2373 binary stars, obtained with the CCD camera on the 1-m Jacobus Kapteyn Telescope at La Palma. The stars are part of the Input Catalogue of the Hipparcos Astrometric Satellite launched in 1989 August, and the purpose of our measurements is to assist in the s…