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Ultraviolet, optical and infrared observations of the intermediate polar TV Columbae.
Szkody, P.; Mateo, M.; Hutchings, J.
Forty-three IUE spectra of the X-ray discovered, triply periodic cataclysmic variable, TV Col are examined. The results show that the UV flux varies with the four-day period discovered by Motch in 1981. By fitting continuum models to the UV and optical fluxes, it is inferred that this modulation corresponds to the periodic heating of a normally 90…
Variations in the variability of RR Tel.
Manfroid, J.; Heck, A.
The visible-light periodicity of the very slow nova RR Tel is inferred to vary in cycles of 350- to 410-day periods, based on the uvby photometric data, IUE FES measurements, and AAVSO visual estimates. Besides a general increase in magnitude, the visible lightcurve is also marked by two events corresponding to sudden decreases of brightness in 19…
Study of Rapid Variability in CYGNUS-X-1
Page, C. G.
The EXOSAT Medium Energy instrument has been used with the new HER6 mode to study the rapid variability of Cygnus X-1. It was found that the fluctuations in the higher energy band (5 - 14 keV) lagged behind those in the lower band (2 - 5 keV) by about 6 milliseconds. This confirms predictions of the inverse Compton model and gives an upper limit t…
IUE observations of the Seyfert 1.9 galaxy Markarian 423.
Rudy, R. J.; Puetter, R. C.; Cohen, R. D.
UV observations of the Seyfert 1.9 galaxy Markarian 423 show a moderately strong UV continuum in the 1200-2000 A region, a strong narrow Lyman-alpha conponent, and no detectable broad lines. This absence of broad UV lines, in conjunction with the steep broad line Balmer decrement, indicates that the gas giving rise to the broad emission lines is s…
Observation of an X-Ray Outburst and Quiescent Emission from the Rs-Canum Binary HR1099
Barstow, M. A.
The RS CVn binary HR1099 has been observed with the medium energy (ME) and low energy (LE) experiments on EXOSAT. X-ray emission was detected from two quiescent components with temperatures ∼4.5 × 105K and ∼4 × 107K, which were observed to flare during the observation. The data are compared with models of coronal behaviour. A…
Upper limits to coronal line emission from X-ray detected T Tauri stars.
Penston, M. V.; Johnstone, R. M.; Lago, M. T. V. T.
High dispersion AAT spectrograms of the two T Tauri stars, GW Orionis and T Tauri, are used to set upper limits to the intensities of the coronal emission forbidden line of Fe XIV at 5303 A. Comparison made with the intensities of chromospheric and the transition-region emission lines, and of the X-ray flux, shows that in GW Ori the Fe XIV forbidd…
UV and optical observations of nova Sagittarii 1982.
Mazeh, T.; Netzer, H.; Cacciari, C. +6 more
Ultraviolet and optical observations of Nova Sagittarii 1982, are presented and discussed. The light curve and continuum energy distribution give a distance estimate of 4.7 kpc, visual extinction of 1±0.3 mag and Mv(max) = -6.35±0.5 mag. Simultaneous ultraviolet and optical data obtained 4 d after visual maximum, enable to study in deta…
UV fluxes of population II stars.
Cacciari, C.
A catalogue of IUE ultraviolet fluxes and calibrated plots for 36 metal-poor field halo stars is presented. The fluxes at 5 Å intervals cover the wavelength range λλ1155 - 3195, or λλ1955 - 3195 for cool stars. For all these stars absolute energy distributions in the visual are available in the literature. The purpose of the present collection of …
UV and optical observations of PG 1351+64, a bright Seyfert galaxy ORA low-luminosity QSO.
Tanzi, E. G.; Falomo, R.; Treves, A. +3 more
PG 1351+64 was repeatedly observed in 1979 - 83 with IUE. Variations of a factor of 2 in both line and continuum intensity were observed with a time-scale of ≡1 month. Coordinated optical observations suggest that the ultraviolet variability is not accompanied by optical variability, so that the overall energy distribution changes shape. The prope…
He 2-36 : a planetary nebula with a high-velocity jet ?
Feibelman, W. A.
The ultraviolet spectrum of the planetary nebula He2-36 was observed in the low-dispersion mode of the IUE. Strong emission lines of C III], He II, and C IV are observed, as well as some weak lines and a moderately strong stellar continuum, suggesting a hot companion to the visual A2 III central star. The extinction to He2-36 was determined from t…