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Transition region structure in F dwarfs.
Saxner, M.
Strong transition region line emission detected in the IUE spectra of two F dwarfs is discussed. The corresponding surface fluxes are found to be comparable to those of active binaries, such as RS CVn-systems. Line flux ratios formed from the multiplets Si IV 1394 A + 1403 A, C IV 1549 A, and N V 1240 A are used in deriving the structure of the tr…
Evidence for autoionization and dielectronic recombination of SI II in the atmospheres of B-type stars.
Underhill, A. B.
Observations are reported demonstrating that both of the 3s3p3d 2F0 levels of Si II autoionize in the atmospheres of B-type stars. A justification is given for concluding that the 2F05/2 level which lies below the laboratory position for the 3s2(1S) limit of Si II, autoio…
Bolometric corrections of silicon stars.
North, P.
Low-dispersion spectrograms of two peculiar stars and of two normal ones were obtained with the IUE satellite in both wavelength ranges. Semi-empirical bolometric corrections were estimated from the observed ultraviolet fluxes and from theoretical fluxes best fitting the observed Geneva color indices.
IUE observations of X Per, the proposed optical counterpart of the X-ray source 4U 0352+30.
Bianchi, L.; Bernacca, P. L.
The O 9.5 (III-V) pe star X Persei, proposed optical counterpart of the X-ray source 4U 0352+30, has been observed on October 14, 1978, with the SWP Camera on board the IUE satellite in the low and high resolution modes. The ultraviolet continuum, in the range 1000-1900 A, can adequately be fitted to the emergent flux from a model atmosphere havin…
IUE observations of V1331 Cyg.
Mundt, R.; Appenzeller, I.; Chavarria, C. +2 more
Low dispersion IUE spectrograms (at wavelengths of 2200-3200 A) of the unusual T Tauri star V 1331 Cyg have been obtained. The observed UV flux is consistent with the assumption that V 1331 Cyg has a photosphere corresponding to a spectral type near F 0. As in the blue to red spectral range, the observed UV line spectrum (dominated by very strong …
On the nature of the 125 day cepheid V810 CEN (=HR 4511) : IUE spectra.
Pakull, M.; van Genderen, A. M.; Heck, A. +4 more
Low and high resolution IUE spectra of the possible extremely long-period, low-amplitude classical Cepheid V 810 Cen (equals HR 4511), are analyzed to determine the effects of its hot blue companion on the observed optical light - and radial velocity - curves. From these spectra we conclude that the early B - type companion is hardly detectable in…
Ultraviolet observations of two extreme population II stars : detection of chromospheric emission and mass loss.
Spite, M.; Caloi, V.; Spite, F.
We describe some spectroscopic features in the ultraviolet and visible ranges for two extreme Population II stars. These features can be interpreted as indicating mass loss.
The ultraviolet spectrum of the eclipsing binary ZET Aur.
Hack, M.
The ultraviolet spectrum of the atmospheric binary Zeta Aur has been observed with the IUE, in the high resolution mode, at the 0.91 and 0.27 spectrum phases. The phases were computed from the epoch minimum light, using the epoch and period given by Kukarkin et al. (1969), and from the periastron passage, using the epoch given by Wright (1970). Th…
Analysis of the far ultraviolet emission lines in late type stars.
Rego, M.; Fernandez-Figueroa, M. J.; de Castro, E. +1 more
Far ultraviolet emission lines in a sample of seven stars of spectral type later than F5 and different luminosity class have been analyzed to calculate the electron density and pressure in the formation region of the lines. Three different methods were used. We obtain electron pressures larger than solar for all dwarf stars of the sample. The low …
Ultraviolet spectrophotometry of the galactic globular cluster M5.
Altamore, A.; Capuzzo-Dolcetta, R.; Angeletti, L. +1 more
Ultraviolet low-resolution observations of M5 (NGC 5904) obtained with the International Ultraviolet Explorer (IUE) Satellite are presented. General characteristics of the spectrum are discussed. A low E(B-V) value was confirmed; some spectral features were identified as being of stellar origin. Broad- and narrow-band fluxes and their spatial dist…