Search Publications
X-ray luminosity and the hydrogen-line ratios of quasars and Seyfert galaxies.
Kriss, G. A.
New observations of the Ly-alpha/H-alpha ratio in a set of X-ray-selected active galactic nuclei and an archival study of International Ultraviolet Explorer (IUE) observations of Ly-alpha in low-redshift quasars and Seyfert galaxies have been used to form a large sample (49 objects) for studying the influence of soft X-rays on the enhancement of B…
Two-phase ultraviolet spectrophotometry of the pulsating white dwarf ZZ Piscium.
Holm, A. V.; Bond, H. E.; Panek, R. J. +3 more
Spectra of the pulsating white dwarf ZZ Psc (= G29-38) were obtained using the International Ultraviolet Explorer. By using a multiple-exposure technique in conjunction with simultaneous ground-based exposure-metering photometry, it was possible to obtain mean on-pulse and off-pulse spectra in the 1950-1310 A wavelength range. The ratio of the tim…
Variable, optically thick plasma in the interacting binaries R Arae and HD 207739.
Kondo, Y.; Parsons, S. B.; McCluskey, G. E., Jr.
Two close binaries observed with the IUE, R Ara and HD 207739, exhibit strong variations of spectral energy distribution that indicate the presence of variable, optically thick extrastellar gas. The deepening of the secondary (eclipse-like) minimum toward shorter wavelengths observed in the ultraviolet light curves of R Ara also provides additiona…
C IV and SI IV in the interstellar medium.
de Jong, T.; de Kool, M.
Column-densities are presented of C IV and Si IV along the line of sight to 49 galactic O-stars, derived from IUE spectra. Since these column-densities appear to be uncorrelated with the distance to the background star a truly interstellar origin of these lines can be ruled out. The fact that large column-densities are preferentially observed towa…
A study of depletions within the rho Ophiuchi cloud based on IUE observations of HD 147889.
Joseph, C. L.; Snow, T. P.
Archival IUE data on the deeply embedded Rho Oph cloud star HD 147889 have been used to derive column densities for several species. The poor data quality and limited useful spectral coverage made unambiguous abundances very difficult to deduce, but firm limits could be set. Absolute depletions have been estimated, based on an assumed value of the…
Ultraviolet and X-ray observations of NGC 2264.
Simon, T.; Snow, T. P., Jr.; Cash, W.
Pre-main-sequence stars in the galactic cluster NGC 2264 were observed with the IUE to search for ultraviolet chromospheric and transition region emission lines and with the Einstein Observatory to search for coronal X-ray emission. Fifteen cluster members (and four other stars) of spectral type B - K, ranging in age from 106 to 10…
Discovery of a cataclysmic variable type companion of the M3 III giant 4 DRA with IUE.
Reimers, D.
IUE observations show that the bright (mv∼5) normal M 3 III giant 4 Dra has a blue companion. Its spectrum increases to shorter wavelengths in the IUE short wavelength region and has strong emission lines of high excitation (CIV, NV, CIII, HeII, ...) superimposed. The spectrum of the companion of 4 Dra bears similarity to UV spectra of …
HD 87643 : a B E star with a cold wind.
Selvelli, P. L.; de Freitas Pacheco, J. A.; Faria Lopes, D. +1 more
Ultraviolet observations of the B/e/ star HD 87643 have revealed the presence of a wind in low ionization species with outflow velocities of up to 800 km/s in the Mg II doublet. The dominating species in the spectrum are the once-ionized metals, mostly Fe II. The P Cyg profiles of the Mg II lines have a structure similar to that of the Balmer line…
The First Ultraviolet Studies of the Optical Candidate for the X-Ray Source 1118-61
Coe, M. J.; Payne, B. J.
The X-ray pulsator, 1118-61, discovered in 1975 by the Ariel-5 satellite, has been observed for the first time at UV wavelengths using IUE. Its UV spectrum clearly identifies the optical counterpart as a Be star similar to that seen in other X-ray pulsators. From the 2200 Å absorption feature a distance estimate of ∼ 4 kpc is obtained and the carb…
IUE observations of a starburst disk and the detectability of high redshift galaxies.
Huenemoerder, D. P.; Weedman, D. W.
The high-surface-brightness inner disk of NGC 1068 has been observed with the IUE to determine the ultraviolet spectrum and surface brightness profile. This disk is explained by an intense starburst, requiring formation of 1-2 massive stars/yr, so it is a good prototype for seeking at early epochs in the universe. Calculations of isophotal diamete…