Search Publications
Identification of the 1400 and 1600 A features observed in the ultraviolet spectra of DA white dwarfs
Nelan, E. P.; Wegner, G.
The λ1600 absorption feature in the spectra of cool DA white dwarf stars has been identified as a resonance broadening of Lyα due to the hydrogen quasi molecule. Likewise, the λ1400 absorption feature in the spectra of cool and moderately warm DA white dwarf stars appears to be due to a Lyα satellite line arising from the hydrogen ion quasi molecu…
Ultraviolet spectroscopic observations of HD 77581 (Vela X-1 = 4U 0900-40)
Hammerschlag-Hensberge, G.; Matsuoka, M.; Kondo, Y. +4 more
Ultraviolet spectra of HD 77581 obtained with the IUE satellite in December 1982 and January 1983 are analyzed. The effective temperature is found to be 25,000 + or - 1000 K by comparing its photospheric absorption lines with those in four well-studied B0-B1 supergiants. The distance of 1.9 + or - 0.2 kpc is derived from its luminosity log L/solar…
IUE observations of phase-dependent variatons in WN+O systems.
Koenigsberger, G.; Auer, L. H.
IUE observations of six WN + O Wolf-Rayet (W-R) systems are reported. The periodic variations in five of the systems are shown to result primarily from selective atmospheric eclipses of the O star continuum by the W-R wind. An optical depth distribution of the form tau inversely proportional to radius is suggested for radii greater than 14 solar r…
High-velocity winds in close binaries with accretion disks. II. The view along the plane of the disk.
Mason, K. O.; Cordova, F. A.
The authors present phase-resolved, ultraviolet spectra of the eclipsing cataclysmic binaries RW Trianguli and DQ Herculis. Both stars display N V λ1240, Si IV λ1400, C IV λ1549, and He II λ1640 in emission. The strongest spectral feature in both stars is C IV λ1549. In RW Tri the blue wing of this line extends to velocities of -3000 km s-1
The hydrogen line spectra of narrow-line radio galaxies.
Ferland, G. J.; Osterbrock, D. E.
The results of the first detection of Ly-alpha in a narrow-line radio galaxy are reported. Nearly simultaneous optical and UV observations of 3C 192 and 3C 223 allow the measurement of both Balmer and Lyman decrements. These line ratios are approximate functions of the interstellar reddening and of a parameter which is proportional to the amount o…
Blue companions of cepheids.
Bohm-Vitense, E.; Proffitt, C.
Twenty-one Cepheids, known or suspected to have blue companions, were studied with the International Ultraviolet Explorer satellite. For 13 of them, companions were indeed seen, though they were generally fainter in the UV than expected. For four Population I Cepheids, the suspected companions were not seen. For none of the Population II Cepheids …
Emission lines in the magnetic white dwarf GD 356.
McCarthy, J. K.; Greenstein, J. L.
Spectrographic measurements of the magnetic white dwarf GC 356 are presented, and, two weak emission line Zeeman triplets at H-alpha and H-beta are analyzed. The measurements were carried out using a high signal-to-noise ratio double spectrograph and CCD detectors attached to the Hale 5 meter refector telescope. Multichannel spectrophotometry of G…
The near-ultraviolet spectrum of the high-redshift BL Lacertae object0215+015.
Blades, J. C.; Pettini, M.; Hunstead, R. W. +1 more
Spectra of the luminous high-redshift BL Lac object 0215+015 have been obtained with the IUE from 2300 to 3150 Å and with the AAT from 3040 to 3870 Å. A total of 66 absorption lines were detected, 50 of which can be identified in the six definite and one probable redshift systems ranging from zabs = 1.254 to zabs = 1.719. Str…
On the outer atmospheres of hybrid stars.
Jordan, C.; Dupree, A. K.; Brown, A. +1 more
The authors discuss a variety of ultraviolet observations of four hybrid atmosphere stars, objects which exhibit both cold winds and high-temperature (transition-region) emission. New IUE data confirm that the K3 II stars ι Aur and θ Her are hybrid stars. In addition γ Aql (K3 II) is found to be another hybrid object. The analysis of the emission …
LSS 2018 : a double-lined spectroscopic binary central star with an extremely large reflection effect.
Drilling, J. S.
LSS 2018, the central star of the planetary nebulae DS1, was found to be a double-lined spectroscopic binary with a period of 8.571 hours. Light variations with the same period were observed in U, B, and V; in the wavelength regions defined by the two IUE cameras; and in the strength of the CIII 4647 emission line. The light variations can be accu…