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The Ultraviolet Spectrum of Beta Lyrae
Mazzali, Paolo A.
The high-resolution UV spectrum of Beta Lyrae observed with the IUE satellite between 1980 and 1986 is analyzed. A complete list of line identifications for the entire spectral range of the IUE (1225-3125 A) is presented. The main spectral features are P Cygni profiles of resonance lines of high ionization states typical of stellar winds, some of …
A Survey of Chromospherically Active Stars
Fekel, F. C.; Henry, G. W.; Moffett, T. J.
Photometric and/or spectroscopic observations have been obtained of 52 late-type stars which are suspected or known to be chromospherically active. Although not all types of observations were obtained for each star, these observations include all-sky BVRI Johnson photometry, ultraviolet spectrograms, low-dispersion blue-wavelength spectrograms, an…
Narrow Absorption Components and Variability in Ultraviolet P Cygni Profiles of Early-Type Stars
Howarth, I. D.; Prinja, R. K.
An extensive set of velocity and column density measurements of both narrow absorption components and 'underlying' P Cygni profiles is presented for a sample of 21 main-sequence, giant, and supergiant stars with spectral types B1-O4, selected as having at least one of the NV, Si IV, and CIV resonance doublets unsaturated. To study variability char…
Ultraviolet Extinction toward Five Open Clusters, and the Accuracy of IUE Extinction Measurements
Fitzpatrick, E. L.; Massa, D.
The UV extinction curves of 33 main-sequence B stars in five open clusters are presented and analyzed. An analytic fitting function is introduced which represents the observed curves and codifies the structure of the 2175 A extinction bump. A set of extinction parameters are also defined which describe the shape of the far-UV extinction. These dat…
Ultraviolet Variability and Mass Expulsion from R Aquarii
Hollis, J. M.; Kafatos, M.; Michalitsianos, A. G.
Ultraviolet spectra in the 1200-3200 A range indicate that the extended nebular features which resemble a jet in the peculiar variable R Aquarii (M7e + pec) increased in excitation in 1985. The emission properties of the compact H II region that surrounds the unresolved binary, and those of the extended nebular jet, have been analyzed from low-res…
The Statistical Equilibrium of Hydrogen and Helium in a Radiation Field, with an Application to Interpreting Wolf-Rayet Spectra
Bhatia, A. K.; Underhill, A. B.
A 70-level model helium atom which includes singly and doubly excited states of He I and a 17-level model hydrogen atom are used to solve the equations of statistical equilibrium for helium and hydrogen in a radiation field. The plasma has a velocity gradient, and densities and temperatures typical for the mantles of Wolf-Rayet stars. The emission…
Ultraviolet Observations of Be Stars. II. Superionization in Be Stars of Different Spectral Types
Peters, Geraldine J.; Marlborough, J. M.
The results of an investigation of the dependence of the strength/presence of lines from superionized species (N V, C IV, Si IV) on spectral type and v sin i in the ultraviolet spectra of Be stars are presented. No evidence is found for N V in stars later than B2; this apparent absence may, however, simply reflect problems with the IUE reduction p…
The Ultraviolet Spectrum of Procyon. I. The Atlas from 2030 to 2371 Angstrom
Kondo, Y.; van der Hucht, K. A.; Castelli, F. +2 more
The high-resolution ultraviolet spectrum of Procyon (F5 IV-V) in the range 2030-2371 A is analyzed by using BUSS VIII and IUE data. A detailed identification is performed with the synthetic spectrum method. The theoretical spectrum has been computed with a Kurucz blanketed model, and using an extended and updated version of the Kurucz and Peytrema…
Spectrophotometric and model-atmosphere analyses of the hot DO and DAO white dwarfs from the Palomar-Green survey.
Wesemael, F.; Green, R. F.; Liebert, J.
Recent optical and spectrophotometric observations of all currently known DAO and DO hot white dwarf candidates from the Palomar-Green Survey are presented. The optical observations were carried out using the Kitt Peak National Observatory Intensified Image Dissector Scanner (IIDS) system, the Multiple Mirror Telescope (MMT), and two photon-counti…
Ultraviolet interstellar absorption toward stars in the Small Magellanic Cloud. III. The structure and kinematics of the Small Magellanic Cloud.
Fitzpatrick, E. L.
The structural and kinematic properties of the Small Magellanic Cloud (SMC) were studied by combining IUE satellite observations of individual bright stars (Sk 159 and HD 5980) with existing optical and radio data. It is shown that the SMC has a complex structure due to gravitational interaction with the Milky Way and the Large Magellanic Cloud (L…