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Non-relativistic solar electron events during December 1990: Results from Ulysses
Chaizy, P.; Anderson, K. A.; Lin, R. P. +1 more
Several groups of impulsive flare accelerated non-relativistic solar electron events occurred in November and December 1990. In a total of 18 separate events, most show the characteristic dispersion in arrival times at the Ulysses spacecraft corresponding to travel time for the various particle energy groups. After maximum development, the electro…
HIPPARCOS double star recognition and processing within the FAST consortium
Badiali, M.; Cardini, D.; Emanuele, A. +4 more
The Hipparcos observations are potentially a source of discovery of new systems of double and multiple stars. Procedures have been developed to recognize in the signal parameters the multiplicity of the stellar objects. The principles applied to the recognition of double stars are presented in this paper along with statistical tests. Results based…
A two-wind radiation-driven model for the atmospheric features of beta Lyrae.
Pauldrach, A. W. A.; Puls, J.; Mazzali, P. A. +1 more
The properties of the non-degenerate interacting binary system of β Lyrae (B6.5 II p+BO V) are investigated via the analysis of its mass loss features.
As a first step, it is shown that the UV emission lines, observed in high dispersion by lUE, can be divided into two groups: one including the `superionised' hot-star wind resonance lines (N V…UV spectroscopy of the X-ray binary AC 211 (= 4U 2127+11) in M 15.
Raymond, J. C.; Charles, P. A.; Hassall, B. J. M. +2 more
Time-resolved International Ultraviolet Explorer observations are presented of the low-mass X-ray binary AC211/4U2127 + 11 in the globular cluster M15 (NGC 7078). The spectra show He II 1640-A emission, the flux of which is modulated on the 8.5-hr orbital period of AC211. This modulation and the ratio of He II 1640 A to He II 4686 A and C IV 1550 …
A Spectroscopic Search for Colliding Stellar Winds in O-Type Close Binary Systems. II. Plaskett's Star (HD 47129)
Wiggs, Michael S.; Gies, Douglas R.
New evidence for colliding winds in the massive O-type binary system Plaskett's star is reported. High S/N ratio spectra of the H-alpha and He I 6678 emission lines are presented, and their orbital phase-related variations are examined in order to derive the locations and motions of the high-density gas in the system. Radial velocity cures for sev…
Mesures de vitesses radiales. V. Accompagnement AU sol du programme d'observation du satellite Hipparcos.
Duflot, M.; Burnage, R.; Genty, V. +2 more
The paper presents data on 1070 radial velocity measurements of stars distributed in 39 fields measuring 4 deg x 4 deg. The PPO series of Fehrenbach et al. (1987) and Duflot et al. (1990) is continued using the Fehrenbach objective prism method.
Spectroscopic binary orbits from ultraviolet radial velocities. Paper 9: Y Cygni (HD 198846)
Stickland, D. J.; Lloyd, C.; Pachoulakis, I. +2 more
The paper presents spectroscopic binary orbits of Y Cygni obtained from the results of a three-day observations (covering 16 hours of each day) of this eclipsing binary, made by the IUE satellite at the end of May 1990. Full cross-correlation reduction of high-dispersion spectra secured over the three days allowed the production of an orbital solu…
Optical spectra of dzeta Aurigae systems. IV. The January 1990 eclipse ofHR 2554 : detection of chomospheric absorption and extended plasma at 10 5 K.
Schroeder, K. -P.; Huensch, M.
Eclipse observations of HR 2554 are presented. These observations were obtained simultaneously during the January 1990 eclipse with ESO telescopes and the IUE satellite. Chromospheric absorption and changes in the circumstellar matter were investigated. Improved system parameters were derived from the light curve. For each of the composite spectra…
HIPPARCOS great-circle reduction - Theory, results and intercomparisons
van der Marel, Hans; Petersen, Carsten
In this paper some of the results of the great-circle reduction in the two data reduction consortia (NDAC and FAST) are presented. It is shown that the root-mean-square (rms) error of the great-circle abscissa of stars brighter than 10 mag is between 3-5 milli-arcsec. This is as was expected before launch, even in spite of the fact that the data-s…
IUE observations of H Lyman-α in comet P/Giacobini-Zinner
Feldman, Paul D.; Combi, Michael R.
Comet P/Giacobini-Zinner (1985 XIII) was observed during the flyby of the International Cometary Explorer (ICE) satellite and during the 3 preceding months by the International Ultraviolet Explorer (IUE) satellite. Models for the hydrogen abundance and spatial distribution, which were previously used to reproduce the observed spatial distribution …