Search Publications
Two Compact Planetary Nebulae of Moderate Excitation: NGC 6565 (3-4.5) and NGC 6644 (8-7.2)
Aller, Lawrence H.; Feibelman, Walter; Keyes, Charles D.
Data obtained with an image-tube scanner at the 3-m Shane telescope are combined with IUE data to obtain plasma diagnostics and chemical compositions for two planetary nebulae of moderately high excitation. Theoretical nebular models were calculated using stellar fluxes given by Husfeld et al. (1984) for T(asterisk) = 85,000 K, log g = 4.72, and e…
White Dwarfs in Cataclysmic Variables: Low State IUE Observations of V794 Aquilae, MR Serpentis, and an Ursae Majoris
Szkody, Paula; Mateo, Mario; Downes, Ronald
The authors have obtained IUE low dispersion observations of one nova-like system (V794 Aql) and two AM Her systems (MR Ser and AN UMa) during low or intermediate low accretion rate states. The decreased UV emission during these times was used to place limits on the white dwarf temperatures. When these results are added to the existing data on whi…
Ultraviolet Spectra of the Narrow-Lined Seyfert Galaxies Markarian 573 and Markarian 1388
MacAlpine, Gordon M.
Ultraviolet spectra, obtained with the IUE satellite, are presented for the unusually narrow-lined Seyfert galaxies Mrk 573 and Mrk 1388. The data support class 2 identifications for both galaxies and also suggest the need for more energetic ionizing radiation in the most recently published Seyfert 2 galaxy photoionization calculation.
Optical and Ultraviolet Activity in RT Lacertae During 1985 and 1986
Huenemoerder, David P.
Continued monitoring of optical spectra of RT Lac, a peculiar RS CVn system, showed a large range of activity in the H-alpha line. At times, there was no excess emission or absorption, and at others, much. During active times, the excess emission varied greatly with phase and seemed to come from an extended region. Two UV observations, taken conte…
A Search for the Binary Companion of Polaris
Evans, Nancy Remage
Polaris has a spectroscopic orbit determined from an extensive series of observations as well as a more uncertain astrometric orbit. The determination of its mass and evolutionary state is of considerable interest because it is a low-amplitude classical Cepheid with unusual period and amplitude variations. In this study, IUE spectra are investigat…
IUE Observations of X-Ray Selected Stars
Stocke, John; Bergoffen, Martin J.; Walter, Frederick +1 more
UV spectra for four X-ray-selected bright (V less than 10) late-type (F and G) stars have been obtained in both the long- and short-wavelength cameras of the IUE satellite. The stars were selected because they had the largest ratios of X-ray to optical luminosity for their spectral type, with known binaries being eliminated from the sample in orde…
Abundances of Mercury in Sirius and VEGA
Sadakane, Kozo; Takada-Hidai, Masahide; Jugaku, Jun
The resonance line of Hg II at 1942 Å in Sirius and Vega is analyzed quantitatively based on high-resolution UV spectroscopic data. The spectrum synthesis technique is employed. The abundance of Hg in Sirius (log ɛ(Hg) = 2.5±0.5) is found to coincide with that found in the two normal late B-type stars ν Cap and π Cet. On the other hand, the obtain…
The Loss and Reestablishment of the Wind in 66 Ophiuchi in 1985
Peters, Geraldine J.
Mass loss in the Be star 66 Oph during the first six months of 1985, when the star temporarily lost its wind, is discussed. Both IUE and ground-based CCD observations of Hα have been utilized in this study. Observations of Be stars during such periods of "quiescence" are especially valuable for gaining insight into the mechanisms responsible for t…
Empirical Continuum Modeling for IUE Low-Dispersion Spectra
Ayres, Thomas R.; Bennett, Jeffrey O.
The authors describe a numerical procedure for empirically determining a "continuum" level in low-dispersion spectra from the International Ultraviolet Explorer. They developed the technique for the automated fitting of SWP-LO (1150 Å - 2000 Å) spectra of stars of late spectral type, but it is more widely applicable.
Analysis of IUE Data on V426 Ophiuchi: Outburst and Orbital Variability
Szkody, Paula; Mateo, Mario
Time-resolved IUE spectra throughout two orbits of the dwarf nova V426 Oph during quiescence are presented. It is found that the visual and C IV fluxes remain relatively constant during both orbits, whereas the UV coninua and Mg II lines vary by 20-30 percent. The time scales of this variability are discussed. Analysis of other spectra at brighter…