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Ultraviolet and X-ray observations of the BL Lac PKS 0548-322.
Kondo, Y.; Mushotzky, R. F.; Urry, C. M. +2 more
Spectrophotometric observations of the BL Lac object PKS 0548-322 were made with ultraviolet and X-ray instruments on the IUE and HEAO-2 satellites. Two observations in each spectral region, one set of which was obtained simultaneously are presented. A power law of energy index approximately 1.0 gives a good description of the data from ultraviole…
The UV continuum spectrum of M81
Torres-Peimbert, S.; Peimbert, M.; Bruzual A., G.
From IUE data the absolute continuum spectrum for the nucleus of M81 in the 1200-3200 A range is presented. The spectrum can be fitted by an old stellar population with a small contribution from horizontal-branch stars. It is found that the number of stars with m less than 0.3 solar mass is negligible. An upper limit for the nonthermal contributio…
Evidence for mass loss at polar latitudes in the Be stars Omega Orionis and 66 Oph
Peters, G. J.
IUE observations of the pole-on Be stars Omega Ori and 66 Oph have revealed the unexpected presence of high velocity (-250 to -850 km/sec), relatively narrow (about 1 A) absorption components to the resonance lines of C IV, Si IV, and Si III. The C IV features show structure indicative of multiple shells or clouds. If Omega Ori and 66 Oph are inde…
Optical and ultraviolet observations of the X-ray globular cluster BO 158 in M31
Cacciari, C.; Bianchi, L.; Fusi Pecci, F. +2 more
It is pointed out that the study of the globular cluster system in a galaxy is very important for understanding the formation, dynamics, and chemical evolution of that galaxy. The present investigation represents an attempt to determine the population content of the globular cluster Bo 158 in M31 through the analysis of its energy distribution in …
The detection of ultraviolet photospheric absorption in the spectra of two Wolf-rayet stars.
Fitzpatrick, E. L.
Narrow, unshifted UV absorption lines, principally of Fe v, have been detected in the spectra of two Wolf-Rayet stars, HD 93162 (WN7) and HD 193793 (WC7). Both stars are known to show upper Balmer-line absorption but exhibit no periodic Doppler shifts that might indicate the presence of a companion. If intrinsic to the Wolf-Rayet stars, these line…
A spectrophotometric analysis of the hot helium-rich white dwarf HD 149499 B.
Sion, E. M.; Wesemael, F.; Guinan, E. F.
A comprehensive analysis of the hot helium-rich white dwarf HD 149499 B is presented based on International Ultraviolet Explorer ultraviolet spectra along with available optical spectra and photometry. Line strengths, line profiles, and continuum fluxes are analyzed in terms of a new grid of hot, high-gravity stellar atmospheres of mixed compositi…
International ultraviolet explorer observations of alf Sco.
Bernat, A. P.
IUE observations of the absorption spectrum of Alpha-2 Sco B2.5 V are presented. These lines arise from matter being lost by the red supergiant primary, Alpha-1 Sco M1.5 Iab, which is passing in front of the B star. There is a factor of 30 spread in the hydrogen column densities derived from different elements on the assumption of solar abundance …
International Ultraviolet Explorer observations of the R AQR jet.
Kafatos, M.; Michalitsianos, A. G.
Ultraviolet spectra were obtained with the International Ultraviolet Explorer of the newly discovered optical-radio jet feature in the symbiotic variable R Aquarii. The far-UV continuum of the jet is characterized by strong continuum which rises with decreasing wavelength in the 1200-2000 A wavelength range and is considerably different in appeara…
The interstellar absorption-line spectrum of mu. Oph.
Boehm-Vitense, E.; Cardelli, J.
UV interstellar lines have been measured on high-resolution, long- and short-wavelength IUE spectra of the B8 V star Mu Oph. Column densities for the observed atoms and ions have been determined as well as turbulent velocities. The interstellar spectrum of Mu Oph is similar to the ones for Rho Oph and Zeta Oph. The ionization equilibria of several…
Detection of the 1400 angstrom absorption in the ultraviolet spectrumof the DA white dwarf LB 3303.
Wegner, G.
Low-resolution ultraviolet International Ultraviolet Explorer spectra of the southern white dwarf LB 3303 show the presence of the wavelength 1400 absorption feature reported by Greenstein in the spectrum of 40 Eri B. The equivalent width is 5.7 A, and the measured wavelength is 1394 A. A comparison of the ultraviolet fluxes with model atmospheres…