Search Publications
Star formation and extinction in extragalactic H II regions.
Kunth, D.; Deharveng, J. M.; Lequeux, J. +1 more
Evolutionary models are presented of far UV luminosity, production of ionizing photons, effective temperature, and ejection of heavy elements for an ionizing star cluster. The way in which interstellar extinction in our Galaxy and inside and outside the H II region affects the UV and optical emission of the complex is discussed. Conclusions are de…
A model of V1016 CYG based on the ultraviolet spectrum.
Nussbaumer, H.; Schild, H.
The ultraviolet spectrum of the suspected symbiotic star V 1016 Cygni is interpreted in terms of a single star model. Spectra were obtained at low and high resolutions in the range 1100 to 3200 A by the IUE. From analyses of spectral features including the forbidden Ne V lines, He II UV recombination lines and the continuum flux, an interstellar r…
IUE spectroscopy of cataclysmic variables.
Vogt, N.; Wolf, B.; Krautter, J. +4 more
The continuum flux distribution and line spectra of six cataclysmic variables detected by the IUE are studied. The spectrophotometry with intermediate spectral resolution around seven A allows derivation of extinction values, temperatures, and the sizes of the radiating areas. V603 Aql, RRpic, HRDel, and TT Ari, which have similar absolute dimensi…
IUE and ground-based spectroscopic observations of the S Dor-type LMCvariable R 71 during minimum state.
Stahl, O.; Wolf, B.; Appenzeller, I.
Using the IUE satellite, high resolution UV spectrograms are obtained of the S Dor type variable R 71 in the LMC. The IUE observations are supplemented by coordinated ground-based high dispersion spectroscopy and photometric observations. For the expanding envelope, a surprisingly low temperature of only about 6000 K and an apparently decelerated …
Ultraviolet extinction in the Small Magellanic Cloud.
Ferlet, R.; Lequeux, J.; Prevot, L. +2 more
The considered investigation is concerned with the determination of the UV extinction curve in the Galaxy on the basis of the spectra of stars in the SMC obtained with the aid of the International Ultraviolet Explorer. The determination rests on the comparison of the observed spectral energy distribution of pairs of similar stars with different ex…
Mass loss from O subdwarfs.
Kudritzki, R. P.; Hamann, W. -R.; Gruschinske, J. +1 more
The P Cygni profiles are reproduced by comoving frame calculations, and a determination is made of the wind parameters. Lower limits of mass loss for these stars (HD 49798 and HD 128220 B) are derived, and upper limits for all four objects are estimated on the basis of general considerations. The empirical results are compared with the available t…
R 81 : P CYG of the LMC.
Stahl, O.; Sterken, C.; Wolf, B. +1 more
Photometric UBV observations and spectroscopic high dispersion coude observations of the very luminous B2.5 eq supergiant R 81 of the LMC carried out between 1970 and 1980 at ESO, La Silla, are discussed. It is noted that the most prominent features of the visual spectrum are P Cygni profiles of the Balmer lines, which are thought to indicate a sh…
Variability of the continuum and the emission lines in the Seyfert 1 galaxy Akn 120.
Kollatschny, W.; Yorke, H. W.; Fricke, K. J. +1 more
Far UV study on the non-thermal activity in the narrow line galaxies NGC 4507 and NGC 5506.
Maccacaro, T.; Bergeron, J.; Perola, C.
The narrow line high excitation galaxies NGC 4507 and NGC 5506 were observed with IUE satellite in the low resolution mode. The continua of both galaxies, when combined with optical observations, show a flattening at log nu greater than 14.9. The reddening correction cannot be estimated with accuracy. The energy content in the Lyman continuum is l…
Photometric orbit of the massive system RY Sct.
Strazzulla, G.; Milano, L.; Vittone, A. +3 more
The UBV lightcurves of RY Scuti were analyzed using the Wilson and Devinney approach (1971). The system is found to be an evolved overcontact system, embedded in a gas and dust envelope, revealed by forbidden lines and IR excess. It is suggested that RY Scuti has early-type components of 39 and 49 solar masses, making it one of the most massive co…