Search Publications
Missions
Journals
Publication Years
Detailed observations of NGC 4151 with the IUE - III. Variability of the strong emission lines from 1978 February to 1980 May.
Tanzi, E. G.; Tarenghi, M.; Perola, G. C. +8 more
Observations of the variability of the three strong ultraviolet emission lines in the Seyfert galaxy NGC 4151 (C IV, C III] and Mg II) are used to study the structure of the broad line region and the nuclear energy source of this active galaxy. Data on the line profile variations further permit the kinematic mapping of the broad line region throug…
IUE observations of high-redshift quasars.
Schmidt, M.; Green, R. F.; Heckman, T. M. +5 more
The authors have measured the continuum energy distributions of nine high-redshift quasars (1.0 ≤ z ≤ 2.2) with the IUE and the Palomar 5 m multichannel spectrophotometer. Generally, the spectral energy distributions steepen at a rest wavelength of about 1200 Å, from a power law, in the optical, of spectral index α ≈ -0.5, to a spectral index of -…
Gamma rays from atomic and molecular gas in the large complex of clouds in Orion and Monoceros.
Caraveo, P. A.; Strong, A. W.; Hermsen, W. +4 more
COS-B gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros are compared with the Columbia CO survey and the Berkeley H I surveys of this region. A good correlation between the gamma-ray emission and the total gas distribution is found. The observed gamma-ray emission can be explained in terms of interactions of…
Selective excitation of Fe II in the laboratory and late-type stellaratmospheres.
Jordan, C.; Johansson, S.
Low resolution spectra of cool giants and supergiants observed with the International Ultraviolet Explorer (IUE) satellite contain emission features for which it has been difficult to establish unambiguous identifications. High resolution spectra of RR Tel and Beta Gru (M 3 II) show lines which can be definitely attributed to Fe II. The presence o…
X-ray observations of a large sample of cataclysmic variable stars using the Einstein Observatory
Mason, K. O.; Cordova, F. A.
This paper presents the results of an X-ray survey of 31 known or suspected cataclysmic variables. Eighteen of these close binary systems are detected with inferred luminosities in the 0.1 - 4.0 keV band of between 1030 and 1032erg s-1. The majority have relatively hard X-ray spectra (kT > 2 keV) irrespective of…
The dust around R Coronae Borealis type stars.
Holm, A. V.; Wu, C. -C.; Hecht, J. H. +1 more
Measurements taken by the International Ultraviolet Explorer spacecraft of the stars RY Sgr and R CrB have been analyzed using Mie theory. The extinction data, which show a 2400-2500 A peak, are consistent with a distribution of 5-60 nm glassy or amorphous carbon particles obscuring the stellar flux. The data are also fairly consistent with a clou…
Spectroscopy of the shell episode of η Car (1981-1983).
Stahl, O.; Wolf, B.; Zanella, R.
High-dispersion spectra of η Car obtained in March 1974, Dec. 1981, and Feb. 1983 have been compared. The spectrum of Dec. 1981 shows conspicuous deviations from the usual spectral appearance of η Car; all lines originating from high ionization and/or excitation levels have dramatically faded. The P Cygni characteristics of the Balmer lines are mo…
Mass loss in O-type stars : parameters which affect it.
Conti, P. S.; Garmany, C. D.
Newly determined mass loss rates are presented for sixteen O-type stars in three open clusters. Combining the data with that already in the literature, no evidence is found that the rates are different in clusters with differing galactocentric distances and compositions, at least near the sun. There is still appreciable dispersion in the relations…
Ultraviolet spectral morphology of the O stars : the remarkable luminosity dependence of the SI IV stellar wind effect.
Walborn, N. R.; Panek, R. J.
An extensive survey of ultraviolet O type spectra, by means of high-resolution data from the International Ultraviolet Explorer archives, shows a strong correlation between both the photospheric and stellar wind features, and the optical spectral types. In particular, the stellar wind effect in the Si IV resonance doublet displays a strong luminos…
Spectrophotometry of two complete samples of flat radio spectrum quasars.
Gaskell, C. M.; Baldwin, J. A.; Wampler, E. J. +1 more
Spectrophotometry of two complete samples of flat-spectrum radio quasars show that for these objects there is a strong correlation between the equivalent width of the C IV 1550 A emission line and the luminosity of the underlying continuum. Assuming Friedmann cosmologies, the scatter in this correlation is a minimum for Q(O) approximately unity. A…