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Magnetic structure in cool stars. V. Chronospheric and transition-region emission from giants.
Zwaan, C.; Oranje, B. J.; Middelkoop, F.
The outer atmospheres of giants at larger heights than the low chromosphere, where the Ca II H and K lines are formed, are studied. In particular, the coupling between the upper chromosphere and the transition region is investigated. G and early K-type giants of different Ca II H and K line-core flux were selected for observations with the IUE. Th…
LB 3459 - an O-type subdwarf eclipsing binary system. Non-LTE analysis of the primary.
Kudritzki, R. P.; Kilkenny, D.; Lynas-Gray, A. E. +2 more
A non-LTE analysis is presented for the primary component of the sdO eclipsing binary LB 3459. The results of the analysis give Teff = 40,000+3000-2000 K, log g = 5.3±O.2 (cgs) and a surprisingly low helium abundance of y = 0.3+O.2-0.1% by numbers. LB 3459 appears to be the result of mass exch…
Mid-infrared observations of Seyfert 1 and narrow-line X-ray galaxies.
Glass, I. S.; Moorwood, A. F. M.; Eichendorf, W.
Broadband 10-micron and 3.8-micron measurements of 6 Seyfert 1 and 5 narrow-line X-ray galaxies are combined with existing near-infrared and optical photometry and UV spectra from the IUE archive in an investigation of the nuclear continua of Seyfert 1 and narrow-line X-ray galaxies. Evidence for a 9.7-micron silicate absorption provided by interm…
Mass loss from extreme helium stars.
Heber, U.; Hamann, W. -R.; Schoenberner, D.
Indications of mass loss are found in the UV spectra of three extreme helium stars (HD 160641, BD -9 deg 4395, and BD +10 deg 2179) obtained with the IUE in high resolution. These three stars are found to lose mass with rates of roughly 10 to the -9th solar mass/yr. These rates have approximately the same order-of-magnitude as expected for 'normal…
Spectral analysis of the OB subdwarf HD 149382.
Kudritzki, R. P.; Scholz, M.; Simon, K. P. +1 more
The ultraviolet and blue spectrum of the OB subdwarf HD 149 382 is analyzed in an investigation of the star's evolutionary status. An effective temperature of 35,000 + or - 2000 K is derived from fitting the observed continuum, hydrogen lines and helium lines to fluxes of unblanketed non-LTE models. LTE analyses of heavy-element lines yield defici…
Chromospheric MG II emission in A5 to K4 main sequence stars from high resolution IUE spectra.
Blanco, C.; Catalano, S.; Marilli, E. +1 more
Observations of the emission cores of the Mg II resonance doublet for 11 main sequence stars in the spectral type range A5-K5 obtained with the IUE satellite at 0.2 A resolution are discussed. Calibrated observed fluxes are used to evaluate the Mg II chromospheric losses as they correlate with effective temperature convection and rotation and othe…
The OB subdwarf Feige 66, a chemical-composition twin to HD 149382.
Hoeflich, P.; Scholz, M.; Baschek, B.
The ultraviolet (1160 to 3230 A) and the blue spectrum of the OB subdwarf, Feige 66, is analyzed differentially to HD 149382. The effective temperature, the surface gravity and the helium abundance of Feige 66 deviate only very little from those of HD 149382. The line spectra are almost identical, and the same strange abundance pattern as in HD 14…
The interacting early-type contact binary SV Cen.
Wolf, B.; Drechsel, H.; Rahe, J. +1 more
Extensive optical and UV observations of SV Cen (b1 V + B6.5III) were obtained between 1978 and 1981. Orbital elements and absolute dimensions were derived from the data. The period-time diagram between 1894 and 1981 shows a large rate of period decrease of -2.15 x 10 to the -5th/yr in average, which exhibits pronounced variations with time. The u…
The ultraviolet spectrum of CH CYG during the outburst started in 1977.
Hack, M.; Selvelli, P. L.
The ultraviolet spectrum of the symbiotic star CH Cygni during the outburst phase that started in 1977 and continues to the present is described, with a discussion of the spectroscopic mechanisms able to explain the emission lines. A mechanism that can explain both the presence of the intersystem line lambda 1641.3 O I and the anomalous intensity …
IUE data reduction - The parameterization of the motion of the IUE reseau grids and spectral formats as a function of time and temperature
Bohlin, R. C.; Thompson, R. W.; Turnrose, B. E.
Improvements are made on IUE data reduction using corrected reseau positions and dispersion constants for temperature variations and secular effects. Models describing the motion of the high dispersion spectral format as a function of THDA alone reduce the scatter in the predicted position of a given wavelength, and scatter is further reduced when…