Search Publications
DA White Dwarf Effective Temperatures Determined from IUE Lyman-Alpha Profiles
Wesemael, F.; Holberg, J. B.; Basile, J.
The Lyman-alpha profiles of 12 DA white dwarfs have been obtained with the International Ultraviolet Explorer Satellite. Analysis of these profiles provides an improved, uniform, and relatively bias-free measure of effective temperature for these stars over the range 20,000-60,000 K. Simultaneous estimates of surface gravity yield a mean gravity o…
Interstellar Abundances in Dense, Moderately Reddened Lines of Sight. I. Observational Evidence for Density-dependent Depletion
Joseph, Charles L.; Crutcher, Richard M.; Snow, Theodore P., Jr. +1 more
The nature of dust-gas interactions, which are capable of modifying the size distribution of interstellar grains and thus causing changes in the selective extinction curve, are investigated through depletion studies. The gaseous abundances of 15 elements have been determined for several lines of sight toward moderately reddened stars, each having …
IUE observations of comet Halley during the Vega and Giotto encounters
Feldman, P. D.; A'Hearn, M. F.; Weaver, H. A. +9 more
The observations of comet Halley from the International Ultraviolet Explorer (IUE) satellite from 9 to 16 March 1986 allow a comprehensive study of gas and dust production by the comet in the week during which the fleet of six spacecraft from four space agencies encountered the comet. The gaseous output of the nucleus was found to vary over timesc…
Comet Halley-solar wind interaction from electron measurements aboard Giotto
Anderson, K. A.; Reme, H.; Korth, A. +9 more
Measurements made by the three-dimensional electron spectrometer of the RPA-Copernic experiment aboard the Giotto spacecraft give a preliminary description of the complex interaction between comet Halley and the solar wind. As Giotto approached the comet, it traversed several regions of differing plasma characteristics: a large (~107 km…
Measurements of Balmer emission line profiles for southern Be stars. II. New data and radial velocities.
Bouchet, P.; Dachs, J.; Hanuschik, R. +6 more
The results of an analyses of more than 500 H alpha, H beta and H gamma line profiles from 55 bright Be and mostly early type Be shell-type stars over the period 1980-83 are reported. The photoelectrically-determined spectra were reduced for equivalent widths and half-widths at different epochs, 200 Balmer line profiles and variations, and radial …
EXOSAT Observations of V471 Tauri: A 9.25 Minute White Dwarf Pulsation and Orbital Phase Dependent X-Ray Dips
Sion, E. M.; Guinan, E. F.; Swank, J. H. +3 more
New results obtained from a 28 hr continuous observation of V471 Tauri with the EXOSAT satellite are reported. The detection of soft X-ray fluxes from both the white dwarf and the K dwarf, the discovery of a 9.25 minute pulsation from the white dwarf, and the discovery of orbital phase-related soft X-ray dips are discussed. The dips may be correla…
Constraints on the outer atmospheric structure of late-type giant stars with IUE : methods and application to Arcturus (alpha Boo K2III).
Judge, P. G.
Methods for empirically analyzing the emission lines formed in the outer atmospheres of late-type low-gravity stars are described and applied to the K2III star Alpha Boo. The methods are based on electron-density measurements, emission-measure analysis, and determination of the optical depths of emission lines. The reduction and measurement of IUE…
The ultraviolet spectrum and interstellar environment of HD 50896.
Howarth, Ian D.; Phillips, A. Paul
By combining the results from 52 IUE spectra of the WN5 star HD 50896 the authors have constructed a photometrically precise, flux-calibrated, mean high-resolution (R ≈ 104) data set covering the wavelength range 1150 - 3274 Å. They give measurements of fluxes and widths for all detected emission lines and P Cygni profiles; approximatel…
Magnetic structure in cool stars. IX. Ultraviolet emission lines from chromospheres and transition regions.
Oranje, B. J.
A compilation of ultraviolet fluxes from 132 stars in the IUE catalog is analyzed in order to study the power-law relations for chromospheric and transition region lines. Flux-flux plots covering 5 decades for transition-region lines and 3.5 decades for chromospheric lines indicate tight power-law relations in the case of single stars, particularl…
Near-simultaneous Ultraviolet and Optical Spectrophotometry of T Tauri Stars
Goodrich, Robert W.; Herbig, G. H.
A set of near-simultaneous ultraviolet and optical spectra and UBVR(J)I(J) photometry of five T Tauri stars has been analyzed for the shape of the energy distribution shortward of 3000 A. The far-ultraviolet continua of these stars are very much stronger than the level of light scattered from longer wavelengths in the IUE spectrograph. The results…