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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…
Two New Bl-Lacertae Objects Discovered in the Error Boxes of Hard X-Ray Sources
Tagliaferri, G.; Beuermann, K.; Branduardi-Raymont, G. +6 more
Two new BL Lacertae objects, located within the error boxes of hard X-ray sources, have been discovered during a systematic program to identify a large sample of EXOSAT serendipitous sources. Both hard X-ray sources were detected during the HEAD 1 whole sky survey and have been associated to a Seyfert galaxy and to a Be star. The EXOSAT data are c…
Anomalously high intercombination line ratios in symbiotic stars; extreme Bowen pumping ?
Feibelman, W. A.; Bhatia, A. K.; Kastner, S. O.
International Ultraviolet Explorer observations of the ratio of the O III intercombination lines near 1660 A are assembled, showing that the observed ratios in symbiotic stars are significantly higher than the theoretically predicted optically thin limit of 2.5. The presence of an enhancing physical process is thereby indicated. It is suggested th…
The EXOSAT Spectral Survey of Bl-Lacertae Objects
Maccagni, D.; Tagliaferri, G.; Giommi, P. +3 more
The results of an analysis of the X-ray spectra of seventeen BL Lacertae objects measured in 66 observations are presented. The 0.1 - 10 keV spectra of these objects exhibit convex curvature in the log F - log plane. This curvature is intrinsic to the continuum . No evidence for high energy tails is found, at least below energies of 8 - 10 keV, no…
EXOSAT observations of the remnant of SN 1006.
Jones, L. R.; Pye, J. P.
The remnant produced by the supernova explosion of AD 1006 has been studied in X-rays with the Exosat Observatory. Images in the energy range 0.1-2 keV with resolution sufficient to resolve the limbs, obtained through three different filters, reveal a limb-brightened nebula containing clumps of emission and displaying large spectral variations wit…