Search Publications
Atmospheric parameters of the variable DB white dwarf GD 358.
Koester, D.; Weidemann, V.; Vauclair, G. +3 more
This paper presents new observations of GD 358, the prototype of the class of variable white dwarfs with helium-dominated atmospheres (DB). These data, together with previous observations, are analyzed using new model atmosphere calculations. The results are Teff = 24000±1000K, log g = 8.0±0.3. This temperature is within the range predi…
Star formation and chemical abundances in the blue compact galaxy ESO338-IG04.
Bergvall, N.
The blue compact galaxy ESO 338 - IG04, which is undergoing a burst of star formation, is luminous for its type and has extremely blue colors. Attention is given to new broadband UBVIR photometry, spectroscopy, and both direct photographic and CCD observations of this galaxy, together with the reanalysis of a low resolution IUE spectrum. In H-alph…
The development of the new Be phase of 59 CYG in the visual and in the far UV in 1978-1983.
Bolton, C. T.; Grady, C. A.; Stalio, R. +10 more
A tentative synthesis of visual and IUE observations of 59 Cyg during 1978-1983 when the new Be phase began to develop is presented. The study reveals correlation between those spectral features originating in the cool H-alpha-emitting envelope and features originating in superionized regions exhibiting C IV and N V lines. The long-term variabilit…
Models for the planetary nebulae NGC 4361 and NGC 1535 : influence ofthe stellar wind on the nebular ionization.
Koeppen, J.; Adam, J.
Model atmospheres fitted to line profiles of the central stars (Méndez et al., 1981) are used to construct nebular ionization models for the planetary nebulae NGC 4361 and 1535. For NGC 4361 the optical and IUE nebular emission lines are reproduced satisfactorily well. For NGC 1535 the model atmospheres only emit less than 10-3 of the n…
The old nova V603 AQL : an intermediate polar ?
Haefner, R.; Metz, K.
A total of 1510 UVB photometric observations obtained with the 50-cm telescope at ESO in 13 6-h runs during July-August 1981 and two-channel polarimeter measurements obtained at the 60-cm Bochum and 1-m telescopes at ESO during the same period are reported for the old nova V 603 Aql. The data are presented in graphs and tables and characterized in…
The interstellar radiation field and the production of inverse-Compton gamma rays in the Galaxy
Bloemen, J. B. G. M.
An empirical model for the large-scale galactic distribution of the various components of the interstellar radiation field is constructed using recent observations, and the spectral and spatial distribution of inverse Compton (IC) gamma ray production in the Galaxy is determined using the most recent estimate of the interstellar electron spectrum …
Magnetic structure in cool stars. VIII. The MG II H and K surface fluxes in relation to the MT Wilson photometric CA II H and K measurements.
Zwaan, C.; Oranje, B. J.
Data from IUE observations of 14 F, G, and K stars of luminosity II-V in the Mg II h + k lines are presented in tables and compared with published Mt. Wilson photometry of the Ca II H + K lines, and empirical relations are derived to facilitate the use of Ca II H + K data in investigating the chromospheric structure of cool stars. The results are …
The ultraviolet spectra of normal elliptical galaxies : a population synthesis approach.
Perola, G. C.; Nesci, R.
Published UV spectra of elliptical galaxies are compared with the results of population syntheses (based on HB stars, accreting white dwarfs in binary systems, or young stars forming in bursts) in an attempt to explain the observed upturn shortward of 200 nm. The results are presented in tables and spectra and discussed in detail. Good agreement i…
UV and optical observations of variability in the WR+compact candidate HD 96548.
Smith, L. J.; Lloyd, C.; Walker, E. N.
The present IUE SWP high resolution spectra of the WR+ compact candidate HD 96548 exhibit significant variability in the P Cygni and emission line profiles. A reanalysis of previously published visible photometry in light of new data shows that all the photometry is periodic, with a period of 5.879 d or its one-day aliases at 0.855 and 1.204 d. Th…
The ultraviolet spectrum of the symbiotic star HM Sge.
Nussbaumer, H.; Mueller, B. E. A.
The authors present IUE fluxes of the symbiotic star HM Sge, extracted from IUE observations made during the years 1978 - 1983. They argue in favour of an accretion disc model. They suggest that the sudden flux increase in He II and the more highly ionized atoms were due to a decrease from a high mass accretion rate, leading to a luminosity above …