Search Publications
Evidence for a warm wind from the red star in symbiotic binaries.
Stencel, R. E.; Friedjung, M.; Viotti, R.
A systematic redshift of the high ionization resonance emission lines with respect to the intercombination lines is found from an examination of the ultraviolet spectra of symbiotic stars obtained with IUE. After consideration of other possibilities, this is most probably explained by photon scattering in an expanding envelope optically thick to t…
The ultraviolet variability of the symbiotic star HBV 475.
Schmutz, W.; Nussbaumer, H.
Evidence is presented for the binary nature of the symbiotic star HBV 475 ( = V 1329 Cyg), based on ultraviolet observations taken with the International Ultraviolet Explorer. The fluxes in the emission lines and in the continuum observed during 1978-1982 are related. It is found that the changes in the line and continuum fluxes observed in the fa…
Detection of a stellar prominence of the K supergiant 32 Cyg.
Schroeder, K. -P.
Light curves at various UV wavelengths have been determined from a sequence of high resolution IUE spectra taken around the 1981 eclipse of 32 Cyg B. Attention is given to the first detection of a stellar prominence of the K supergiant, seen as a transient absorption of the B star continuum flux whose mechanism is probably Rayleigh scattering at t…
The old-nova GK Per (1901). III. Accretion disc models.
Bianchini, A.; Sabadin, F.
The UV spectrum of the old-nova GK Per (1901) at quiescence greatly differs from those of the other observed old-novae. In spite of the presence of high excitation emission lines, the UV to visual continuum energy distribution is peaked at ≡3600 Å, whereas for most old-novae it steeply rises towards shorter wavelengths. The authors have constructe…
Models of the planetary nebulae IC 2003, NGC 3242, 6210 and 7009 : constraints on the ionizing radiation of the central star.
Koeppen, J.
Using ultraviolet, optical, and infrared emission line data, ionization models for four planetary nebulae are constructed. In the fitting procedure, we place emphasis on [O III] λ500.9 nm and [O III] λ436.3 nm to reproduce both the ionization and thermal balance in the O++ zone. The ratios C IV λ155.0 nm/C III] λ190.8 nm, N IV] λ148.7 n…
Envelope structure of the cyclic V/R variable shell stars.
Baade, D.; Hubert, H.; Hirata, R. +4 more
The radial velocity measurement in the far ultraviolet and visual spectra of two V/R variable shell stars, ζ Tau and 48 Lib, has been performed. The radial velocities of once and twice ionized elements in the far ultraviolet region coincide with those of the visual shell lines, while the radial velocities of more ionized elements, such as Si IV an…
The O IV infrared and ultraviolet flux ratios as temperature and density diagnostics.
Nussbaumer, H.; Hayes, M. A.
New fine-structure collision strengths for transitions among the levels of the first two terms of O+3 are presented. The density sensitivity of the intensity ratios of the components of the intercombination multiplet at 1401 Å is re-evaluated for densities and temperatures applicable to planetary nebulae. The authors also show that the …
Profiles and intensity ratios of the C IV lambda 1548, 1550 emission lines in planetary nebulae.
Feibelman, W. A.
The C IV resonance doublet at lambda 1548, 1550 is an important diagnostic tool in the study of planetary nebulae. The predicted theoretical intensity ratio of 2:1 is, however, rarely observed in the high dispersion IUE spectrograms. Values of 0.8-2.0 are observed for a sampling of 11 planetary nebulae of various excitation classes and for three p…
MG II profile variations of zeta Aurigae.
Kondo, Y.; Chapman, R. D.; Ahmad, I. A.
The authors have observed variations in the Mg II 2800 Å doublet of Zeta Aurigae. The Mg II profiles deviate from simple P-Cygni profiles in that they exhibit an absorption feature consistent with Chapman's (1981) interpretation of C IV absorption as evidence of a column of accretion onto the B star component of the binary. The authors find the op…
The dust envelope of the Herbig AE star, AB Aur.
Catala, C.
Ultraviolet low resolution observations of a Herbig Ae star, AB Aur, when compared with a theoretical energy distribution for the same spectral type, show the existence of an anomalous extinction, which is believed to be due to a circumstellar dust envelope surrounding the star. The study of this anomalous extinction allows the author to determine…