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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…
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 …
The magnetically controled stellar wind of HD 21699.
Sonneborn, G.; Shore, S. N.; Brown, D. N.
The authors report the discovery of a magnetically controlled stellar mass outflow in the helium-weak sn star HD 21699 = HR 1063. IUE observations show that the C IV resonance doublet is variable on the rotational time scale of about 2.5 days, and that there are no other observable spectrum variations in the UV. The magnetic field reverses sign on…
EXOSAT soft X-ray observations of EX Hydrae.
Kahn, S. M.; Mason, K. O.; Cordova, F. A.
During a continuous 26 hour X-ray observation of the 98-min binary EX Hydrae using the CMA detector on EXOSAT, a 67-min modulation was detected with a pulse-fraction of about 30 per cent. The phase of the modulation coincides with that of the 67-min optical modulation which has a pulse-fraction of 15 per cent. The X-ray and optical pulse shapes ar…
Ultraviolet interstellar absorption toward stars in the Small Magellanic Cloud. III. The structure and kinematics of the Small Magellanic Cloud.
Fitzpatrick, E. L.
The structural and kinematic properties of the Small Magellanic Cloud (SMC) were studied by combining IUE satellite observations of individual bright stars (Sk 159 and HD 5980) with existing optical and radio data. It is shown that the SMC has a complex structure due to gravitational interaction with the Milky Way and the Large Magellanic Cloud (L…