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Atmospheric parameters and carbon abundance of white dwarfs of spectral types C2 and DC.
Koester, D.; Weidemann, V.; Zeidler, E. -M.
Model atmosphere calculations over a wide range of effective temperatures and carbon abundances are used to analyze IUE data obtained between 1200 and 3200 A as well as photometric and spectroscopic data in the visible region for several sets of white dwarfs of spectral types C2 and DC. The carbon abundances relative to helium are found to range f…
On the linearity of the SWP camera of the IUE : a correction algorithm.
Bohlin, R. C.; Cassatella, A.; Schiffer, F. H. +2 more
An algorithm is presented for correcting IUE low resolution spectral images obtained with the SWP camera for some of the non-linearity effects reported by Bohlin et al. (1980). The non-linearity problem, which affects SWP images processed at Goddard Space Flight Center in the period May 22, 1978 to July 7, 1979 and at VILSPA in the period June 14,…
Shell and photosphere of OMI ORI E : new observations and improved model.
Groote, D.; Hunger, K.
Phase-dependent IR fluxes in the J, H, K, L, and M bands, together with visual spectrograms and IUE spectra, are used to study the helium-rich star Sigma Ori E. An effective temperature of about 22,500 K is derived, along with an angular diameter of 0.079 milliarcsec, a surface gravity of log g equals 3.85, and a mass of approximately 3 solar mass…
Detection of further red giants with "Hybrid" atmospheres ANS a possible correlation with double circumstellar MGII and CAII lines.
Reimers, D.
In addition to the three known hybrid atmosphere stars (Alpha and Beta Aqr, and Alpha TrA), the three red giants (Theta Her, Iota Aur and Delta TrA) which have both transition layer lines (N V, C IV, Si IV, C II) and cool winds have been detected. It is shown that all six known hybrid stars have double circumstellar Ca II and Mg II absorption line…
Production of CS and S in Comet Bradfield /1979 X/
Feldman, P. D.; Jackson, W. M.; Halpern, J. B. +1 more
High and low resolution ultraviolet spectra of carbon monosulfide (CS) in Comet Bradfield (1979 X) were obtained with the IUE satellite. The high resolution rotational profile of the (0, 0) band at 257.5 nm can be fitted with a theoretical profile derived assuming a Boltzmann temperature of 70 K. Spatial plots of the low resolution data for both S…
IUE observations of dwarf novae during active phases.
Stahl, O.; Vogt, N.; Wolf, B. +4 more
Spectra of six dwarf novae during active phases were observed with the IUE in the low resolution mode in order to study different types of outburst behavior and to investigate physical processes during outbursts. Results were obtained for continuum energy distribution and interstellar extinction, temperatures and spectral indices, line spectra, an…
SK 143 : an SMC star with a galactic-type ultraviolet interstellar extinction.
Lequeux, J.; Prevot, L.; Prevot-Burnichon, M. -L. +2 more
The ultraviolet extinction curve (1200-3000 A) deduced from IUE observations of the Small Magellanic Cloud star Sk 143 is presented. This curve is rather similar to the galactic one, with a large bump at 2200 A and a smaller rise shortward of 2000 A compared to the SMC extinction curve of Rocca-Volmerange et al. (1981). The N(H)/E(B-V) ratio estim…
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…