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Outer atmospheres of cool stars. XI. High-dispersion IUE spectra of five late-type dwarfs and giants.
Moos, H. W.; Stencel, R. E.; Linsky, J. L. +4 more
We present high-dispersion, far-ultraviolet (1150-2000 Å) spectra of five late-type dwarfs and giants obtained with the International Ultraviolet Explorer. The chromospheric (T ≲104K) emission lines in the giants tend to be about twice as broad as the corresponding features of the dwarf star spectra, suggesting a width-luminosity relati…
Intense Lyα emission from Uranus
Durrance, S. T.; Moos, H. W.
The existence of intense atomic hydrogen Lyα emission from Uranus is demonstrated here by utilizing the monochromatic imaging capabilities of the International Ultraviolet Explorer (IUE) spectrograph. Our observations show increased emission in the vicinity of Uranus superimposed on the geocoronal/interplanetary background. If resonant scattering …
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 circumstellar extinction of RY Sgr.
Holm, A. V.; Wu, C. -C.; Doherty, L. R.
In 1979-80, ultraviolet spectrophotometry of RY Sgr was obtained by the International Ultraviolet Explorer (IUE) during the star's recovery from its 1977-78 minimum. The wavelength dependence of the extinction of this R Coronae Borealis-type variable was determined by comparison of spectra obtained at different times but with nearly the same pulsa…
The chromospheres of classical Cepheids. I - Low resolution IUE spectra
Parsons, S. B.; Schmidt, E. G.
A program to study the behavior of chromospheres in classical Cepheids using both ground-based and satellite-based observations. Five stars, delta Cep, nu Aql, beta Dor, zeta Gem, and l Car, have been included, and where possible the various types of data have been obtained simultaneously. The first part of this investigation concerns low dispersi…
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…
International Ultraviolet Explorer observations of hyades stars.
Antiochos, S. K.; Stern, R. A.; Zolcinski, M. C. S. +1 more
A description is presented of International Ultraviolet Explorer (IUE) satellite observations of transition region and chromospheric emission from a group of Hyades dwarfs which are strong X-ray emitters as seen in a survey conducted by Stern et al. (1981). Short-wavelength spectra (1175-2000 A) and long-wavelength spectra (1900-3200 A) have been …
Ultraviolet absorption by highly ionized atoms in the Orion Nebula.
Savage, B. D.; Franco, J.
The International Ultraviolet Explorer was used to obtain high-resolution, far-UV spectra of theta 1 A, theta 1 C, theta 1 D, and theta 2 A Orionis. The interstellar absorption lines in these spectra are discussed with an emphasis on the high-ionization lines of C IV and Si IV. Theta 2 A Ori has interstellar C IV and Si IV absorption of moderate s…
First ultraviolet observations of two new cataclysmic variables 1E 0643-1648 and 4U 1849-31.
Motch, C.; Bonnet-Bidaud, J. M.; Mouchet, M.
The two hard X-ray sources 1 E0643-1648 and 4U 1849-31 have been observed in the range 1200-3200 Å with I.U.E.. They show ultraviolet spectra typical of cataclysmic variables. The distances inferred from the ultraviolet interstellar extinction are 300 pc and 600 pc respectively for 1 E0643-1648 and 4U 1849-31.
The line spectrum is characteriz…