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A Time-Series IUE Archival Study of the White Dwarf in the Ultrashort-Period Dwarf Nova WZ Sagittae
Sion, E. M.; Cheng, F. H.; Slevinsky, R. J. +2 more
The IUE archive offers a series of far-UV spectra of the ultrashort-period dwarf nova WZ Sge over a long time baseline and hence the opportunity to monitor the ongoing accretion, the cooling of the white dwarf, and temporal variations in the line spectra. We have carried out a quantitative analysis of these spectra including model atmosphere simul…
The CaII-M_v Correlation (Wilson-Bappu Effect) Calibrated by HIPPARCOS Parallaxes
Wallerstein, George; Machado-Pelaez, Laura; Gonzalez, Guillermo
We have used Hipparcos parallaxes to derive absolute visual magnitudes of G, K, and M stars with Ca II emission line widths previously measured by O. C. Wilson. A linear relationship similar to the one derived originally by Wilson & Bappu and improved by Lutz & Kelker was found from M_v=+7 to -2. For stars brighter than M_v=-2 a substantia…
A Study of the Time-dependent Background and Continuum Flux Levels in IUE High-Dispersion SWP Images
Smith, Myron A.
The extraction of net spectral fluxes from echellogram images for the creation of the final International Ultraviolet Explorer (IUE) archive was accomplished by the processing system NEWSIPS computing a background surface from unilluminated pixels over a wide area of the image for any given echellogram order. Although this technique facilitates th…
Adaptive Optics Observations of Arcturus using the Mount Wilson 100 Inch Telescope
Mason, Brian D.; ten Brummelaar, Theo A.; Turner, Nils H.
Upon inspection of the multiple-star results in the Hipparcos catalog, the flag for entry number 69673 particularly stands out; it is Arcturus, for which no companion has been reported previously. The Hipparcos companion is reported to be at a separation of 0.255"+/-0.039" with a magnitude difference in a broadband filter (peaked near 460 nm) of 3…
The Early Palomar Program (1950-1955) for the Discovery of Classical Novae in M81: Analysis of the Spatial Distribution, Magnitude Distribution, and Distance Suggestion
Zurek, David R.; Shara, Michael M.; Sandage, Allan
Data obtained in the 1950-1955 Palomar campaign for the discovery of classical novae in M81 are set out in detail. Positions and apparent B magnitudes are listed for the 23 novae that were found. There is modest evidence that the spatial distribution of the novae does not track the B brightness distribution of either the total light or the light b…
The Use of Gamma-Ray Bursts as Direction and Time Markers in SETI Strategies
Corbet, Robin H. D.
When transmitting a signal over a large distance, it is more efficient to send a brief beamed signal than a continuous omnidirectional transmission, but this requires that the receiver knows where and when to look for the transmission. For SETI, the use of various natural phenomena has previously been suggested to achieve the desired synchronizati…
Detection of O VII lambda1522 in IUE Spectra of Planetary Nebula Nuclei and Other Hot Stars
Feibelman, Walter A.
We present the first detection of O VII lambda1522 emission or absorption from archival IUE spectra in 14 planetary nebula nuclei and three PG 1159-type stars. The n=5-->6 transition of O VII was determined by Kruk & Werner and observed by them in the spectrum of the very hot PG 1159-type star H1504+65 from data obtained with the Hopkins Ul…
Intereclipse Spectroscopic Snapshot of epsilon Aurigae with the Hubble Space Telescope
Lambert, David L.; Sheffer, Yaron
A single-epoch low-resolution Goddard High Resolution Spectrograph spectrum of the eclipsing binary epsilon Aurigae was obtained while the secondary was orbiting toward eclipse by the primary. The spectrum as recorded between 1175 and 1461 Å is rich with emission and absorption lines which include stellar and interstellar components. The emission-…
Ultraviolet Evidence for a Binary Nucleus of the Planetary Nebula SH 2-71
Feibelman, Walter A.
Archival IUE spectra of the planetary nebula Sh 2-71 show a variable Mg II lambda2800 emission line superposed on a variable stellar continuum. The Mg II feature is thought to be excited in the chromosphere of the cooler component of a binary nucleus, although other causes are also plausible.
Hubble Space Telescope Astrometric Observations of the Metal-poor Spectroscopic Binary HD 20039
Hershey, John L.; Osborn, Wayne
An attempt has been made to spatially resolve the metal-poor, double-lined spectroscopic binary HD 20039 with the Hubble Space Telescope Fine Guidance System. Astrometric measurements of the system to complement the spectroscopic orbit would permit the distance and the masses of the components to be determined. Observations were obtained around th…