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Astrometric positions of stars associated with nebulosities in the southern hemisphere.
Rousseau, J. M.; Perie, J. P.
Several stars associated with nebulosities and cited by S. van den Bergh and W. Herbst are included in the preliminary programme for the HIPPARCOS mission. When performing preparatory measurements of plates, we encountered difficulties in identifying certain of these objects when relying only on coordinates, which led us to take advantage of this …
Comparison of the Carlsberg optical reference frame with the International Celestial Reference Frame.
Fabricius, C.; Jones, D. H. P.; Morrison, L. V. +4 more
The optical positions of 63 extragalactic nebulae measured in the frame defined by the annual series of Carlsberg Meridian Catalogues Nos 1-8 are compared with their VLBI radio positions in the International Celestial Reference Frame. The differences between these radio and optical positions are interpreted as showing the global distortion of the …
First UV spectrum of the AM Herculis star RX J1940.1-1025.
Staubert, R.; Friedrich, S.; La Dous, C.
We present the first UV spectrum of the polar RX J1940.1-1025, taken with the IUE satellite in the wavelength range between 1190A to 1950A. The phase averaged spectrum shows strong emission lines of CIV (1550A), NV (1240A), SiIV (1397A) and HeII (1640A) which are typical for AM Her stars. The line ratios of NV/SiIV and NV/CIV, and the continuum fl…
Hubble Space Telescope Studies of Exposed White Dwarfs in Dwarf Novae
Sion, Edward M.
Coordinated AAVSO optical observations and Hubble Space Telescope (HST) far ultraviolet (UV) spectroscopic observations of cataclysmic variables, during dwarf nova quiescence when the underlying white dwarf is exposed in the far UV, have yielded a number of new insights into accretional heating, photospheric abundances of the accreted atmosphere, …
Generation of plasma turbulence and radio emission at the front of interplanetary MHD shocks.
Ledenev, V. G.
Based on spectral observations of turbulence and radio emission in the interplanetary medium from the Ulysses spacecraft, we describe processes responsible for the formation of energetic particle fluxes, the generation of Langmuir and ion acoustic turbulence, and the radio emission at the front of a quasi-perpendicular MHD shock wave. It is shown …
The multishell complex in Cygnus: High-velocity motions in the nebula Simeiz 55
Lozinskaya, T. A.; Esipov, V. F.; Sitnik, T. G. +3 more
Local Clouds : Distribution, Density and Kinematics Through Ground-Based and HST Spectroscopy
Gry, Cecile
The distribution, kinematics and physical properties of the interstellar matter surrounding the Sun can be inferred from ground-based and UV spectroscopic observations. On a 200 pc scale the local interstellar matter appears inhomogeneous and asymmetric. Although it generally flows towards the lower density region, it is composed of numerous small…
Branches and loops in the X-Ray colour-colour diagram of Cygnus X-3.
van der Klis, M.; Smit, J. M.
We present an analysis of EXOSAT ME X-ray colour-colour diagrams of Cygnus X-3. Our sample contains all the Cygnus X-3 data collected during EXOSAT's operational life time and covers a total of 190 hours. The colour-colour diagrams display X-ray spectral variations with the 4.8 hour period and show the spectral distinction between the `high' and t…
Analysis of non-planar structures with multipoint measurements
Balogh, A.; Dunlop, M. W.; Motschmann, U. +2 more
The advent of multi-spacecraft space missions like CLUSTER provides a new challenge for maximising the information return from data taken of complex magnetic field structures in the Earth's plasma environment using a spacecraft magnetometer. Most challenging are those structures which are not amenable to single spacecraft analysis techniques such …
UV survey of δ Scuti stars: Final results and open problems
Pasinetti Fracassini, Laura E.; Pastori, Livio
The results obtained from our IUE observations of some δ Scuti stars and in particular 71 Tau and 69 Tau are reviewed. 71 Tau is the second brightest X-ray source of the Hyades cluster; on the contrary 69 Tau, very similar to 71 Tau in the optical range, does not show X emissions. The complex and in somewhat controversial scenario obtained from th…