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The Complex Wind of the Central Star of the Planetary Nebula Abell 78
Feibelman, Walter A.; Kaler, James B.; Henrichs, H. F.
The authors have observed with the high-dispersion camera of the IUE the broad P Cygni profiles of C IV, N V, and O V that arise from Abell 78's nucleus. They find a terminal velocity to the wind that is close to 3670±30 km s-1, a positive velocity gradient, and an approximate mass loss rate of ≡4×10-9M_sun;yr-1. S…
The Ultraviolet-Optical-Infrared Energy Distribution of LMC X-3: Observation of an Accretion Disk around a Black Hole
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +4 more
LMC X-3 was observed quasi-simultaneously at UV (IUE), optical, and IR (ESO, La Silla) frequencies in 1987 January. The overall energy distribution exhibits a broad peak around 10^15^ Hz. The UV flux appears well in excess of that measured by us in 1986 March, which can be attributed to the noncollapsed star in the system. The excess emission can …
Quasi-simultaneous Ultraviolet Optical and Infrared Observations of the BL Lacertae Object PKS 0048-09
Maraschi, L.; Tanzi, E. G.; Bouchet, P. +2 more
The first International Ultraviolet Explorer (IUE) observations of the BL Lacertae object PKS 0048-09 were obtained on 1987 January 7 and 8, when the object was in a moderately high optical state (m_v_ ~ 15.5 mag). Quasi-simultaneous optical-IR spectrophotometry allows deriving the detailed energy distribution from ~10^14^ to ~2.5 x 10^15^ Hz. Com…
High resolution cluster method for topological studies of the light curves of gamma-ray pulsars.
Buccheri, R.; Sacco, B.; di Gesu, V. +1 more
The authors describe a non-parametric, binning-free, adaptive method for the detection and the analysis of structures in the light curves of gamma-ray pulsars, based on a clustering technique. They use computer simulated data and a sample of COS-B data relative to the Vela pulsar to show its behavior and robustness. As a main result they find that…
The ultraviolet to X-ray continua of BL Lac objects.
Warwick, R. S.; George, I. M.; McHardy, I. M.
We present the results from EXOSAT observations of three X-ray bright BL Lacertae objects, Mrk 501, 1218+304 and MRK 180. All three sources have soft power-law X-ray spectra with low-energy cut-offs consistent with absorption in the line-of-sight gas column density through our own galaxy. The three objects also exhibit significant spectral variabi…
White Dwarfs in Cataclysmic Variables: Low State IUE Observations of V794 Aquilae, MR Serpentis, and an Ursae Majoris
Szkody, Paula; Mateo, Mario; Downes, Ronald
The authors have obtained IUE low dispersion observations of one nova-like system (V794 Aql) and two AM Her systems (MR Ser and AN UMa) during low or intermediate low accretion rate states. The decreased UV emission during these times was used to place limits on the white dwarf temperatures. When these results are added to the existing data on whi…
Magnesium abundances in planetary nebulae and interstellar absorptionof MG II lambda 2800 A.
Middlemass, D.
High-resolution IUE images have provided line profiles of emission cut by interstellar absorption in the magnesium II lines λλ 2795, 2802 Å in nine objects. The underlying emission has been reconstructed in seven of these and estimates of the ratio of intrinsic to observed emission ranging from 1.5 to 23 have been obtained. Photoionization models …
Cooling Flow in the 2A 0335+096 Cluster of Galaxies
Singh, K. P.; Westergaard, N. J.; Schnopper, H. W.
We present the surface brightness distribution of hot intracluster gas in the 2A 0335+096 cluster of galaxies, obtained from X-ray imaging observations with the Einstein Observatory and the EXOSAT Observatory. The intracluster gas is found to be nonisothermal. The surface brightness is deprojected to obtain density and temperature profiles of the …
Ultraviolet Spectroscopy of R Coronae Borealis
Holm, A. V.; Doherty, L. R.
Observations of the hydrogen-deficient supergiant R CrB were obtained with the IUE over an interval of 54 days in order to study the nature of this star's irregular, small-amplitude variations in light. By chance, the series of observations coincided with a dip in the light intermediate between the normal fluctuations and the deep declines associa…
The Spacelab-1 very wide field survey of UV-excess objects. I. CPD -71 172 AB, a new binary with a hot subdwarf.
Burgarella, D.; Cassatella, A.; Prevot, L. +1 more
The images taken with the Very Wide Field Camera aboard Spacelab-1 have revealed a variety of stellar objects with strong UV excess. UV(IUE) and ground-based observations of the first object identified (CPD -71°172) have demonstrated a binary system comprising a cool, moderately-evolved star (F3-F4 IV), and a hot OB subdwarf with Teff ≈…