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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…
Comparison of winds in the Small Magellanic Cloud and galactic early-type stars.
Bruhweiler, F. C.; Wray, J. D.; Parsons, S. B.
IUE low-resolution spectra of 11 OB stars in the Small Magellanic Cloud reveal considerably lower wind velocities than corresponding galactic stars. The reduced effectiveness of radiative acceleration due to lower abundances of heavy elements in the SMC is believed to be responsible for this effect. The absorption strengths of the SMC P Cygni prof…
Luminosities and masses for three central stars of planetary nebulae in the Magellanic clouds from ultraviolet spectroscopy with the IUE.
Gull, T. R.; Stecher, T. P.; Maran, S. P. +2 more
Physical parameters of the central stars of the planetary nebulae (PN) P40, N2, and N5 are determined from UV observations by the IUE spacecraft and emission line-data. The observations took place on May 23 and 26, 1981. Derived properties, such as the H-beta, color excess, nebular hydrogen emission, helium emission, and stellar continuum emission…
Ultraviolet, visual, and infrared observations of the WC7 variable HD193793.
Savage, B. D.; Fitzpatrick, E. L.; Sitko, M. L.
Low-resolution IUE data are used to explore the ultraviolet extinction toward the Wolf-Rayet star HD 193793 and to search for ultraviolet variability that might relate to the infrared variability. High-dispersion IUE observations are used to investigate the nature of the stellar wind of the star and to search for anomalies in the interstellar line…
Ultraviolet observations of the 1980 eclipse of the symbiotic star CICyg.
Kafatos, M.; Stencel, R. E.; Michalitsianos, A. G. +1 more
The paper presents secular and eclipse variations of ultraviolet lines and continua in the course of nearly a complete orbit of CI Cygni. High-excitation resonance lines show minimal effects of eclipse, while intercombination lines have faded and show pronounced but nontotal eclipse effects. The observations are examined in terms of mass transfer …
Magnesium emission variability among late-type giant stars.
Stencel, R. E.; Mullan, D. J.
Profiles of the Mg II h and k emission features in the spectra of 21 late-type giant stars were obtained. Emission strengths were separately measured in the shortward (S) and longward (L) components. Variations in total emission intensity (S + L) can be interpreted as evidence for variations in the rate of mechanical energy deposition in the chrom…
Outer atmospheres of cool stars. X. HR 1099 at quadrature.
Linsky, J. L.; Ayres, T. R.
IUE high-dispersion, far-UV spectra of the active-chromosphere RS CVn binary HR 1099 are reported. The emission features produced by such high-temperature species as C II and C IV are found to be very bright, to exhibit structure, change significantly in the one-week interval separating the two exposures, and generally follow the radial velocity m…
IUE observations of proto-planetary and variable planetary nebulae. II. A search for variability in IC 4997 and NGC 6905.
Feibelman, W. A.
A search for ultraviolet variability was conducted for the planetary nebulae IC 4997 and NGC 6905 which have histories of variability in the visible region. Emission line fluxes, line ratios, line profiles, and central stars' temperatures are presented for both objects, as well as stratification effects for several ions in NGC 6905.
The MG II resonance lime emission at 2800 angstrom in stars with different rotational velocities and different metal abundances.
Boehm-Vitense, E.
In many investigations, a study of the Mg II 2800 A emission was conducted in order to derive more information about the correlation of chromospheric emission with the properties of the convection zone. It has been suggested by Ayres and Linsky (1980) that there is a positive correlation between rotation and chromospheric emission at least for bin…