Search Publications
Ultraviolet Observations of SN 1987A
Kirshner, Robert P.; Sonneborn, George; Crenshaw, D. Michael +1 more
UV observations of the supernova in the LMC, SN 1987A, were carried out with the IUE satellite. The earliest data show that the UV flux from the supernova was already declining while the optical flux was still rising. The UV spectrum at these epochs consists of broad features associated with the supernova atmosphere punctuated by sharp interstella…
The beta Pictoris circumstellar disk. IV. Redshifted UV lines.
Ferlet, R.; Vidal-Madjar, A.; Lagrange, A. M.
Several new and archive observations with the International Ultraviolet Explorer have confirmed the variability of the UV circumstellar absorption lines of Fe II and Mg II toward β Pic. The authors furthermore show that all these variations take place on the red wing of the lines, in material which is moving toward the star. Tentative scenarios ar…
The Dependence of Ultraviolet Chromospheric Emission upon Rotation among Late-Type Stars
Simon, Theodore; Fekel, Francis C., Jr.
The authors have obtained low-resolution IUE spectra of a large number of chromospherically active stars. Integrated fluxes of chromospheric and transition region emission lines have been measured. These fluxes, supplemented by published observations and measurements of IUE archival spectra, have been used to search for correlations between activi…
Discovery of a strong soft X-ray excess in MKN 335 - evidence for an accretion disc ?
Turner, T. J.; King, A. R.; Pounds, K. A. +2 more
Exosat observations of Mkn 335 reveal a hard power-law spectrum above about 1 keV, typical for Seyfert 1 galaxies, but with unusually strong variability on time-scales of about 1-2 hr. In addition, an intense soft X-ray component is found to dominate the overall spectrum of Mkn 335 below about 0.6 keV. Both soft and hard components increased in st…
The radio to X-ray continuum emission of the quasar 3C 273 and its temporal variations.
Bouchet, P.; Falomo, R.; Gear, W. K. +7 more
Quasi-simultaneous multifrequency observations from radio to X-rays of the bright quasar 3C273 for several epochs between December 1983 and March 1986 are presented. The light curves in the different wavebands and the overall spectral energy distribution are analyzed. The NIR and optical fluxes showed small variations during the period considered,…
A detailed analysis of the high energy gamma-ray emission from the Crab pulsar and nebula.
Grenier, I. A.; Hermsen, W.; Bennett, K. +4 more
The gamma-ray emissions from the Crab pulsar and nebula are analyzed. The data were collected from 1975-1982 in the Galactic anticenter region by COS-B in the energy range 50-3000 MeV. The temporal behavior of the pulsed gamma-ray flux from PSR 0531 + 21 and the unpulsed gamma-ray emissions from the Crab region are examined. It is determined that …
Physical Parameters for 12 Planetary Nebulae and Their Central Stars in the Magellanic Clouds
Gull, Theodore R.; Aller, Lawrence H.; Maran, Stephen P. +3 more
Nebular and central star parameters and elemental abundances of C, N, O, Ne, S, and Ar are presented for the planetary nebulae N2, N5, N43, N54, and N67 in the SMC and P2, P7, P9, P25, P33, and P40 in the LMC. The nebular chemical compositions are affected by nuclear processes in the precursor stars, which may not have been sufficiently massive to…
Highly Ionized Stellar Winds in Be Stars: The Evidence for Aspect Dependence
Grady, C. A.; Snow, T. P.; Bjorkman, K. S.
The authors present the results of an ultraviolet survey of stellar winds in 62 Be and 43 normal B stars covering spectral types B0.5 - B5 and luminosity classes V - III. They find that the wind absorption seen in the resonance lines of C IV, Si IV, and Si III in Be stars is often the result of blended absorption from multiple shortward-shifted di…
Evidence for Chain Molecules Enriched in Carbon, Hydrogen, and Oxygen in Comet Halley
Anderson, K. A.; Reme, H.; Korth, A. +7 more
In situ measurements of the composition and spatial distribution of heavy thermal positive ions in the coma of comet Halley were made with the heavy-ion analyzer RPA2-PICCA aboard the Giotto spacecraft. Above 50 atomic mass units an ordered series of mass peaks centered at 61, 75, 91, and 105 atomic mass units were observed. Each peak appears to b…
The Progenitor of SN 1987A: Spatially Resolved Ultraviolet Spectroscopy of the Supernova Field
Kirshner, Robert P.; Sonneborn, George; Altner, Bruce
Careful deconvolution of spatially resolved IUE ultraviolet spectra shows that only two of the three stars detected in plate material before 1987 are now present near the site of SN 1987A. The separation, magnitudes, and spectra of these two are consistent with their identification as star 2 and star 3 of the Sanduleak -69°202 trio. The clear impl…