Search Publications
X-Ray Luminosity and Spectral Variability of Hard X-Ray--selected Active Galactic Nuclei
Tagliaferri, G.; Giommi, P.; Grandi, P. +2 more
One hundred sixty-one observations archived in the EXOSAT data base are analyzed in order to study time and spectral variability of all 30 sion-line active galactic nuclei (AGNs) in the Piccinotti sample. For each source long-term (from days to months) and short-term (from minutes to hours) luminosity variations were sought using the soft (LE: 0.0…
The Broad Emission-Line Profiles and Profile Variability of the Seyfert 1 Galaxy Arakelian 120
Korista, Kirk T.
We present Hα and Hβ broad emission-line profiles of the Seyfert galaxy Arakelian 120 from the past ~10 yr, representing over 100 spectroscopic observations. The broad emission-line profiles of the Balmer lines are complex in structure and variable; the profile variations themselves are complex. We attempt to isolate separate emitting components w…
The Colorado IUE Active Galaxy Survey. I. Blazars
Shull, J. M.; Kinney, Anne; Edelson, Rick +2 more
This paper presents consistently reduced ultraviolet continuum flux densities and spectral indices derived from all 499 usable archived IUE observations of blazars made through mid-1991. The extraction of one-dimensional spectra and the measurement of spectral parameters are discussed. A detailed error analysis is presented, including a discussion…
The Orbital Parameters and the IUE Spectrum of the Single-lined Spectroscopic Binary HD 698
Sahade, Jorge; Barba, Rodolfo; Kondo, Yoji
IUE observations of the spectroscopic binary HD 698 show that its continuous spectrum corresponds to that of a B5 III-II object and that, even in the ultraviolet, the object is single-lined. The spectrum displays several sets of lines, all in absorption, where features can be distinguished that partake of the orbital motion of the B5 component, li…
Structure and Kinematics of the Broad-Line Regions in Active Galaxies from IUE Variability Data
Koratkar, Anuradha P.; Gaskell, C. Martin
IUE archival data are used to investigate the structure and kinematics of the broad-line regions (BLRs) in nine active galactic nuclei (AGNs). The cross-correlation technique, for unevenly sampled data, advocated by Gaskell and Sparke has been applied to spectra taken between 1978 and 1988. An extensive investigation of the errors has been carried…
An Ultraviolet Atlas of Quasar and Blazar Spectra
York, D. G.; Blades, J. C.; Bohlin, R. C. +1 more
We have constructed an ultraviolet atlas of 69 quasars, blazars, and Seyfert 1 galaxies by combining over 1000 low-resolution spectra drawn from over a decade of observations contained in the IUE data archive. In order to optimize the signal-to-noise ratio, the spectra have been reextracted and co-added. The IUE spectra show that quasars and blaza…
Predicted Profiles of Ultraviolet Interstellar Absorption Lines
York, D. G.; Welty, D. E.; Hobbs, L. M.
In this paper, values of the column density, line width parameter, and velocity are determined for as many components derived from optical interstellar absorption-line profiles of Na I and K I as needed to reproduce the observed high-resolution optical profiles of the D lines of Na I toward eight lightly reddened stars and of the 7698 A line of K …
Fe II Emission Lines. I. Chromospheric Spectra of Red Giants
Judge, P. G.; Jordan, C.
A 'difference filtering' algorithm developed by Ayers (1979) is used to construct high-quality high-dispersion long-wavelength IUE spectra of three giant stars. Measurements of all the emission lines seen between 2230 and 3100 A are tabulated. The emission spectrum of Fe II is discussed in comparison with other lines whose formation mechanisms are…
A Spectrophotometric Atlas of White Dwarfs Compiled from the IUE Archives
Wegner, Gary; Swanson, Steven R.
Ultraviolet spectrophotometric data are presented for 182 subluminous stars, mostly white dwarfs, that have been observed with the low-resolution mode of the IUE satellite since 1978 and for which archived data became available on April 1, 1989. Tables of 20 A binned data are given for all stars. Of these, 133 cover the entire wavelength range of …
The Interoutburst Behavior of Cataclysmic Variables
Szkody, Paula; Mattei, Janet A.; Waagen, Elizabeth O. +1 more
Existing IUE and AAVSO archive data were used to accomplish a large scale study of what happens to the UV flux of accretion disk systems during the quiescent intervals between outbursts, and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 n…