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An X-ray and optical study of the low-mass X-ray source 4U 1556-605.
Motch, C.; Beuermann, K.; Pakull, M. W. +1 more
Partly simultaneous EXOSAT and optical observations of the low-mass X-ray binary 4U 1556-605 are presented. X-ray flux variations of relatively small amplitude (about 20 percent) are accompanied by a significant hardening of the X-ray spectrum. This behavior is investigated in the framework of several currently proposed spectral models. The optica…
An Interpretation of the Line Profile Variations in the IUE Spectrum of the Wolf-Rayet Binary gamma 2 Velorum
Sahade, Jorge; Brandi, Estela; Ferrer, Osvaldo E.
An analysis of the variable profiles of the high-temperature resonance lines of Si IV in the IUE spectrum of gamma(2) Vel has made it possible to describe these profiles as a superposition of two different profiles, namely, a P Cygni profile that remains practically stationary throughout the orbital cycle and an absorption profile that moves back …
Line Identifications in the Ultraviolet Spectrum of 31 Cygni
Bauer, Wendy Hagen; Stencel, Robert E.
Line identifications are presented for the Zeta Aur-type eclipsing binary system 31 Cyg (K4 Ib + B4 V). The rich absorption spectrum observed during chromospheric eclipse has been nearly completely identified. This list will be useful in analyzing spectra of related binaries, such as 32 Cyg and VV Cep. The large number of line transitions contribu…
High-resolution Hα spectroscopy of the bright RS CVn system HR 7275.
Eker, Zeki
HR 7275 is a bright, long-period (28 day), single-lined RS CVn binary. High-resolution (0.36 A) and good signal-to-noise ratio echelle spectra do not show any clear evidence of the secondary in the system on spectral lines. Also, absence of a continuum on a low-resolution UV spectrum (IUE merged log) and the known mass function imply a main-sequen…
High resolution IUE observations of the flare star AD Leonis : implications for the MG II Wilson-Bappu effect.
Pettersen, B. R.; Ambruster, C. W.; Sundland, S. R.
The first high resolution IUE observations of the classical M dwarf flare star, AD Leonis is reported. For the Mg II h and k emission lines (2795 and 2803 A), no variation in the line strength, width, or flux is found in four spectra spanning 24 hr. The lines are broader in AD Leo than in AT Microscopii and AU Microscopii, the only other M dwarfs …
Interstellar Gas and Large Grains toward HD 38087
Snow, Theodore P.; Witt, Adolf
High-dispersion IUE spectra have been obtained of HD 38087, a star associated with reflection nebulosity where 2175 A scattering has previously been observed. The presence of 2175 A in emission implies unusually large grains, an attempt was made to see how these unusual grains may have affected the depletions of gas-phase elements onto dust in the…
A study of the ultraviolet spectrum of VV Cephei.
Hack, M.; Engin, S.; Yilmaz, N.
The IUE images of the atmospheric eclipsing binary VV Cep (M 2 Ia e + B, P = 20.3 yr) were studied. The absorption and emission lines in the high-resolution spectra were identified. No interstellar absorption lines were detected despite the large degree of reddening. The comparison of the UV energy distribution of VV Cep after the end of the eclip…
Terminal Velocity of Wind, Mass Loss, and Absorption Lines in the Central Star of the Planetary Nebula 75 +35 1
Feibelman, Walter A.; Bruhweiler, Frederick C.
The high-galactic latitude planetary nebula 75 + 35.1 deg was observed in the high-dispersion mode of the International Ultraviolet Explorer (IUE) satellite in the wavelength range 1150-1950 A. The N V resonance doublet at 1240 A and O V subordinate line at 1371 A exhibit strong stellar P Cygni profiles with absorption extending to -2150 km/s and …
Model Atmospheres and Parameters of Central Stars of Planetary Nebulae
Patriarchi, P.; Perinotto, M.; Cerruti-Sola, M.
Non-LTE hydrogen and helium model atmospheres have been obtained for temperatures and gravities relevant to the central stars of planetary nebulae. Low-resolution and high-resolution observations obtained by the IUE satellite have been used along with optical data to determine Zanstra temperatures of the central stars of NGC 1535, NGC 6210, NGC 70…
The variable Herbig AE star HR 5999. IX. Variability in the UV shell lines.
The, P. S.; Tjin A Djie, H. R. E.; Blondel, P. F. C.
The young Herbig Ae star HR 5999 has been observed with the IUE in high resolution for six different phases of brightness. The equivalent width and half-width of a set of low excitation lines are measured. Both quantities appear to be correlated with the variation of the stellar magnitude in the sense that they decrease in strength with decreasing…