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Ultraviolet, visual, and infrared observations of the WC7 variable HD193793.
Savage, B. D.; Fitzpatrick, E. L.; Sitko, M. L.
Low-resolution IUE data are used to explore the ultraviolet extinction toward the Wolf-Rayet star HD 193793 and to search for ultraviolet variability that might relate to the infrared variability. High-dispersion IUE observations are used to investigate the nature of the stellar wind of the star and to search for anomalies in the interstellar line…
On the detection of abundance stratifications in peculiar stars through the curve of growth method
Alecian, G.
Theoretical curves of growth for manganese are computed for an atmosphere with T(eff) = 12,000 K and log g = 4. It is shown that the curves of growth may be strongly affected by the presence in the atmosphere of a plane parallel layer where manganese is overabundant. The theoretical results are compared with observations of the Hg-Mn star Nv Her. …
On excitation through radiative pumping of the Fe II UV-mult. 191 lambda lambda 1785-88 angstrom observed with the IUE during the eclipse of 32 Cyg.
Reimers, D.; Hempe, K.
We show by means of high-resolution lUE spectra of 32 Cyg during and shortly after eclipse - there is a total eclipse of the B star in the UV - that the Fe II UV-multiplet 191 is pumped via the Fe II resonance UV-multiplet 9 λλ1260-76 Å. We show directly from observations 1. that all absorbed multiplet 9 photons are emitted as Fe II UV Mult. 191 l…
Ultraviolet observations of the 1980 eclipse of the symbiotic star CICyg.
Kafatos, M.; Stencel, R. E.; Michalitsianos, A. G. +1 more
The paper presents secular and eclipse variations of ultraviolet lines and continua in the course of nearly a complete orbit of CI Cygni. High-excitation resonance lines show minimal effects of eclipse, while intercombination lines have faded and show pronounced but nontotal eclipse effects. The observations are examined in terms of mass transfer …
On the search for transition zone lines in late A type stars.
Praderie, F.; Crivellari, L.
Observations of the 1400-1800 A region in late A type stars are presented, which were obtained using the IUE satellite at low and high resolution. The calibrated energy distribution is derived and presents a large variation with wavelength in the spectral range due to Si I photoionization discontinuities. Emission lines formed in the transition re…
Magnesium emission variability among late-type giant stars.
Stencel, R. E.; Mullan, D. J.
Profiles of the Mg II h and k emission features in the spectra of 21 late-type giant stars were obtained. Emission strengths were separately measured in the shortward (S) and longward (L) components. Variations in total emission intensity (S + L) can be interpreted as evidence for variations in the rate of mechanical energy deposition in the chrom…
IUE observations of the Lac object AO 0235+164.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +1 more
AO 0235+164 was observed with IUE during its February 1979 outburst. The object was detected in both the short and long wavelength cameras. Hydrogen Lyman-alpha absorption in the z = 0.524 system is detected with equivalent width of 62 + or - 28 A (1-sigma error). From this and previous 21-cm data, the spin temperature of the absorbing material is…
Outer atmospheres of cool stars. X. HR 1099 at quadrature.
Linsky, J. L.; Ayres, T. R.
IUE high-dispersion, far-UV spectra of the active-chromosphere RS CVn binary HR 1099 are reported. The emission features produced by such high-temperature species as C II and C IV are found to be very bright, to exhibit structure, change significantly in the one-week interval separating the two exposures, and generally follow the radial velocity m…
Stellar wind in the nucleus of IC 2149.
Perinotto, M.; Benvenuti, P.; Cerruti-Sola, M.
Low and high resolution spectra of the planetary nebula IC 2149 obtained with the IUE satellite reveal the existence of a stellar wind in the central star of the nebula. The terminal velocity is found from the CIV gamma 549 profile to be of 1440 plus or minus 100 km/sec. An effort to evaluate the associated mass loss rate gives values around 1/100…
IUE observations of proto-planetary and variable planetary nebulae. II. A search for variability in IC 4997 and NGC 6905.
Feibelman, W. A.
A search for ultraviolet variability was conducted for the planetary nebulae IC 4997 and NGC 6905 which have histories of variability in the visible region. Emission line fluxes, line ratios, line profiles, and central stars' temperatures are presented for both objects, as well as stratification effects for several ions in NGC 6905.