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Fine dust structures in the emission of comet P/Halley observed by the Halley Multicolour Camera on board Giotto
Keller, H. U.; Thomas, N.
Halley Multicolor Camera (HMC) observations on board the ESA Giotto spacecraft provided images of comet P/Halley with resolution 4-orders of magnitude better than from the ground in March 1986. The fine structure seen in the emission from the cometary surface has led to some confusion over the nomenclature of jets and jet-like features streaming f…
Giotto / IMS Observations of Ion Flow Velocities and Temperatures Outside the Magnetic Cavity of Comet p/ Halley
Schwenn, R.; Balsiger, H.; Goldstein, B. E. +8 more
Fluid parameters for He2+ ions obtained from the Giotto Ion Mass Spectrometer HERS sensor are presented; also investigated are proton densities and velocities and thermal speeds of protons, alpha particles, and heavy ions in the hour before closest approach. A bow shock transition lasting ten minutes is observed. A region of enhanced He…
The Interstellar Medium toward Supernova 1987A
Kirshner, R. P.; Sonneborn, G.; Raymond, J. C. +2 more
High-resolution spectra of SN 1987A obtained with the IUE show absorption features from the disk and halo of our Galaxy and the Large Magellanic Cloud. A rich variety of elements and ionization stages is found, including allowed resonance lines of abundant elements with ionization states ranging from C I and O I to Al III, Si IV and C IV. The Si I…
The UV high resolution spectrum of A-type supergiants.
Talavera, A.; Gomez de Castro, A. I.
A study of all the A-supergiants observed with IUE at high resolution shows that they can be divided into two groups: stars which show evidence of wind and mass-loss, and stars which do not show these characteristics. In the first group the resonance lines of Mg II, Fe II, Si II, C II are asymmetric, showing variable shortward shifted components. …
A spectral study of the persistent X-ray flux from 4U/MXB 1636-53.
van Paradijs, J.; Lewin, W. H. G.; Vacca, W. D. +3 more
The authors present a spectral analysis of the persistent X-ray flux from the X-ray burst source 4U/MXB 1636-53, which was continuously observed with EXOSAT for about 25 h in May 1984. They find that no standard one-component spectral model provides an acceptable representation of all the data. However, almost all "complex one-component" and "two-…
New EXOSAT Observations of Tv-Columbae - Preliminary Results
van der Woerd, H.; Brinkman, A. C.; Schrijver, J.
The first results of the analysis of new EXOSAT observations of the DQ Her type cataclysmic variable TV Col are presented. The period of the 1–10 keV X-ray pulsation associated with the white-dwarf rotation is now established as 1911 s. The pulsations are most pronounced in the lower energy channels (1–3.5 keV). The X-ray light curve shows absorpt…
PG 1411+442: The Nearest Broad Absorption Line Quasar
Green, Richard F.; Hutchings, John B.; Malkan, Matthew A.
IUE observations reveal strong, moderately broad absorption troughs in the blue wings of the C IV and N V emission lines of the quasar PG 1411 + 442. No absorption from weakly ionized gas is detected. The emission-line strengths and overall shape of the ultraviolet/optical/near-infrared/far-infrared continuum of the new broad absorption line quasa…
Spectroscopic binary orbits from photoelectric radial velocities. Paper 3: delta Orionis
Howarth, I. D.; Zuiderwijk, E. J.; Stickland, D. J. +1 more
The purpose of the present contribution is to add a modern set of orbital elements to those derived from data of some antiquity in the pursuit of a value for the apsidal motion constant for the bright, hot supergiant δ Orionis.
Ultraviolet Interstellar Extinction toward NGC 6530 and the Intrinsic Energy Distribution of 9 Sagittarii and HD 165052
Torres, Ana V.
The ultraviolet interstellar extinction curve is determined toward 12 early B main-sequence stars and one O8 V star in NGC 6530. The extinction is found to be uniform across the cluster. At short wavelengths, the extinction curve of NGC 6530 falls below the average Galactic curve by a full magnitude, indicating that the population of small grains …
X-ray/optical brightness trends in 3C 66A.
Maccagni, D.; Tarenghi, M.; Garilli, B. +1 more
New X-ray and optical observations of the BL Lac object 3C 66A show small amplitude (≡30%) variability occurring probably contemporaneously in both ranges. The time scale is of the order of a week. This indicates that small intensity variations engage the whole electromagnetic spectrum of the source between visible and X-ray wavelengths, while lar…