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Energy structure of the accretion disc corona in X 1822-371.
Hellier, Coel; Mason, Keith O.; Williams, O. R.
Ginga observations of the LMXB X 1822-371 show that the broad orbital modulation and the eclipse are deeper at higher energies. This is explained if the X-ray emitting corona produces softer emission at greater heights from the disc plane, which suggests that either the corona is optically thick, or that the illuminating X-rays are anisotropic. Fu…
The massive stars in the R136 region of 30 Doradus.
Elson, Rebecca A. W.; Schade, David J.; Thomson, Robert C. +1 more
We present U and B photometry, based on Hubble Space Telescope observations, for 26 stars in the R136 region of the young cluster 30 Doradus in the Large Magellanic Cloud. It has been suggested that rich star clusters form through the coalescence of clumps, and it seems likely that the R136 region is such a clump. If it is in virial equilibrium th…
UV spectroscopy of Z Chamaeleontis. II - The 1988 January normal outburst
Sonneborn, G.; Charles, P. A.; Hassall, B. J. M. +3 more
IUE observations taken during the 1988 January normal outburst of Z Cha are presented and a detailed comparison with the 1987 April superoutburst is made. The most important difference from the superoutburst is that the normal outburst continuum flux shows less than 10 percent orbital variation away from the eclipse, implying that there is no 'coo…
Extensive X-ray monitoring of the broad-line radio galaxy 3C 382.
Giommi, P.; Barr, P.
The results of an intensive monitoring campaign of the X-ray light curve of the broad- line radio galaxy 3C 382, performed using the EXOSAT observatory over a five-month period in summer 1985, are presented. Significant variations on a time-scale of several days are found in both the hard and soft X-ray bands, probably superimposed on a systematic…
Ionizing radiation in the variable active galaxy 3C 120.
Gondhalekar, P. M.
The change in the C IV/Lyα line ratio when the continuum intensity changes, in the spectrum of the radio-loud active galaxy 3C 120, has been modelled. This analysis defines (i) the average parameters of the broad- line region in this galaxy and (ii) the ionizing spectrum seen by the clouds in this region. A soft extreme-ultraviolet continuum is re…
X-ray variability in the Seyfert galaxy Markarian 618.
Singh, K. P.; Rao, A. R.; Vahia, M. N.
We report X-ray observations of the Seyfert type I galaxy Markarian 618, using the low-energy (LE) and the medium-energy (ME) detectors of the EXOSAT observatory. The 0.1-10 keV X-ray spectrum is adequately explained by a simple power law with the photon index {GAMMA} = 1.8^+0.7^_-0.5_( 90 per cent confidence), similar to that observed from variou…
Intrinsic chromospheric emission from dzeta Aurigae binaries.
Eaton, Joel A.
The question of whether the eclipses of Zeta Aur binaries reveal information about the chromospheres of single stars is addressed. It is concluded that Al II 2669 A, and the fluorescent iron lines, as well as CI II 2325 A are formed by the intrinsic thermal processes of the chromospheres of the K supergiant components of the Zeta Aur binaries. Tha…
Resolution of the southern radio lobe of 3C 33 at 660 NM
Stiavelli, Massimo; Crane, Phillipe
An HST planetary camera image of the southern radio lobe of 3C 33 has revealed a strand of emission coincident with the peak in the radio emission at 2 and 6 cm. The detailed morphological similarity between the optical and radio data confirms beyond doubt the common origin of the radio and optical emission, and raises the question of the physical…
Delta CAP - the secondary revealed.
Bromage, G. E.; Kellett, B. J.; Lloyd, C. +5 more
The recent detection of the eclipsing metallic-lined binary Delta Cap in the EUV as part of the Wide-Field Camera All-Sky Survey has prompted a reexamination of the available data in order to attempt to locate the source of the emission. It can be shown that a white dwarf is unable to account for the emission, and the possibility of coronal emissi…
Deconvolution and photometry of Faint Object Camera images with point sources.
Mackay, C. D.; Schade, D. J.; Thomson, R. C. +2 more
The peculiar characteristics of images obtained with the Hubble Space Telescope have raised important questions concerning the proper method for processing data in which the point spread function is seriously distorted. In particular, there is considerable confusion over whether or not it is useful to deconvolve the images, and to what extent the …