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The explanation of the 1400 and 1600 A features in DA white dwarfs.
Koester, D.; Weidemann, V.; Vauclair, G. +1 more
The authors present new IUE observations of 4 cool DA white dwarfs together with additional data for 8 objects from the literature. All objects show absorption features near 1400 and/or 1600 Å, which were already noted by other authors. These features are explained as due to quasi-molecular absorption of the H2 (1600 Å) resp. H2
Peculiar motions and star formation in the interacting galaxy complexMK 171 = NGC 3690+IC 694.
Lequeux, J.; Augarde, R.
Spectroscopic observations in the visible and in the far ultraviolet are combined with other existing information to interpret the properties of the exceptionally active extended star formation in Mk 171. The authors show that this system corresponds to the interaction, and probably to the direct collision, of two galaxies with a total mass of ⪉4×…
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…
Investigation of a wind model for cataclysmic variable ultraviolet resonance line emission.
Verbunt, F.; Drew, J.
The present investigation of ionization and thermal structure in a spherically symmetric, radiatively driven wind emanating from the vicinity of a cataclysmic variable's white dwarf notes that wind ionization is always high for plausible wind and radiation field parameter values, and that resonance scattering dominates line formation at large radi…
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…
Multiwavelength observations of eleven cataclysmic variables.
Szkody, P.
Observations covering nonsimultaneous IUE and optical spectroscopy and broadband optical and infrared photometry of ten dwarf novae (TY Psc, UV Per, TW Vir, V503 Cyg, AF Cam, CM Del, AR And, VW Vul, FO Aql, and CY Lyr) and one novalike system (V425 Cas) at various outburst states are presented. The author uses the multiwavelength coverage to probe…
The continuum variability of the puzzling X-ray three-period cataclysmic variable 2A 0526-328 (TV Col).
Motch, C.; Bonnet-Bidaud, J. M.; Mouchet, M.
TV Col is characterized on the basis of 120-195-nm and 190-320-nm large-aperture low-dispersion IUE spectra obtained between April 1980 and May 1982, UBV measurements obtained with the 1-m telescope at ESO in November 1979 (Motch, 1981), and JHK photometry obtained using the standard IR photometer on the 3.6-m telescope at ESO on Dec. 31, 1982. Th…