Search Publications
Ultraviolet Observations of the Eruption in the Small Magellanic Cloud Wolf-Rayet System HD 5980
Koenigsberger, Gloria; Georgiev, Leonid; Guinan, Ed +1 more
We present results of IUE observations ( lambda lambda 1200--3200) of the erupting system HD 5980 obtained in 1994 November and December. The 1994 spectrum presents emission lines from ions such as N III, Si II--III and Al III which were absent in 1991. There is a systematic tendency towards higher degrees of ionization over the 44 days covered by…
The latitude gradients of galactic cosmic ray and anomalous helium fluxes measured on Ulysses from the Sun's south polar region to the equator
Simpson, J. A.; McKibben, R. B.; Zhang, M. +2 more
Measurements from the Ulysses COSPIN (Cosmic Ray and Solar Particle INvestigations) High Energy Telescope between 80.2°S solar latitude and the sun's equator from September 1994 to March 1995 confirm that the modulated fluxes of galactic cosmic rays and anomalous components depend only weakly on heliographic latitude in the inner heliosphere at th…
Ultraviolet Observations of SW Ursae Majoris, BC Ursae Majoris, and TV Corvi (1217--18): IUE Spectroscopy and Outburst Light Curves
Szkody, Paula; Howell, Steve B.; Sonneborn, George +5 more
We present lUE superoutburst observations of three tremendous outburst amplitude dwarf novae. Limited ground-based optical photometry was also obtained contemporaneously. This is the first such ultraviolet spectroscopy of these systems, and we compare our results with other well-studied dwarf novae of similar orbital periods. We find that the slop…
Surface carbon abundances and compositional stratification of cool helium-rich white dwarfs.
Koester, D.; Weidemann, V.
From the ultraviolet lines of CI in IUE spectra of the DQ white dwarfs L 845-70, GD 84, and G 188-27 we determine a surface carbon abundance of logC/He=-7, and T_eff_=9250, 9000 and 11000K. Comparison with the results for other stars of the same spectral class indicates variations in carbon abundance at the same temperature. If the carbon is the r…
Monte Carlo simulations of the Rayleigh scattering effects in symbiotic stars
Schmid, H. M.
This paper investigates the Rayleigh scattering effects in symbiotic binaries using Monte Carlo simulations. The simulations calculate the scattering path of far-UV photons released from the hot component or from the emission nebula. A large fraction of these photons penetrate into the extended atmosphere and the wind of the cool giant, where Rayl…
SPARTAN 201 Coronal Spectroscopy During the Polar Passes of ULYSSES
Guhathakurta, M.; Strachan, L.; Kohl, J. L. +2 more
Spartan 201 is a shuttle deployed spacecraft that is scheduled to perform ultraviolet spectroscopy and white light polarimetry of the extended solar corona during two 40 hour missions to occur in September 1994 and August 1995. The spectroscopy is done with an ultraviolet coronal spectrometer which measures the intensity and spectral line profile …
The β Pictoris phenomenon among young stars. II. UV observations of the Herbig AE star UX Orionis.
Talavera, A.; Grady, C. A.; Perez, M. R. +4 more
IUE spectra of the Herbig Ae star UX Ori reveal the presence of large amplitude light and color changes, which are an extension to shorter wavelengths of the "blueing" effect seen in the optical. At optical maximum the UV spectrum of UX Ori is dominated by heavy line blanketing from accreting circumstellar gas with velocities as high as +200km/s. …
Ulysses observations from pole-to-pole: An introduction
Smith, Edward J.; Marsden, Richard G.
Recent results from the Ulysses spacecraft as it observed particles and fields above the Sun's south polar cap, returned rapidly across the equator and traversed the northern solar hemisphere are presented in subsequent articles. This introduction provides a brief description of the spacecraft, the experiments, the unique trajectory and highlights…
Extensive dark-matter haloes in low-luminosity galaxies revealed by quasar absorption lines
Barcons, X.; Webb, J. K.; Lanzettat, K. M.
STUDIES of the kinematics of spiral galaxies suggest that dark (possibly non-baryonic) matter is a significant component of their total mass1. It has been difficult to determine how far the dark-matter haloes of galaxies extend, however, because the presence of dark matter must be inferred from the motion of a luminous component such as…
HST Observations of the Core of the Globular Cluster NGC 6624
King, Ivan R.; Sosin, Craig
We have used the Faint Object Camera (FOC) on the Hubble Space Telescope (HST) to observe three fields near the center of the post-collapse globular cluster NGC 6624 in B and V. We use individual stellar positions and a maximum-likelihood technique to measure a position for the cluster center. We then transfer this position and the position of the…