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Neutral Hydrogen Gunn-Peterson Absorption from an Overdensity in the Diffuse Intergalactic Medium at Redshift 0.8?
Turnshek, David A.; Khersonsky, Valery K.; Strub, Sheflynn M.
The results of a search for diffuse neutral hydrogen ``Gunn-Peterson'' absorption, including possible absorption from any overdensity in the diffuse intergalactic medium, at low to moderate redshifts (z < 1.2) are discussed. The relatively low incidence of Lyα forest lines at these redshifts makes this work more straightforward than would be th…
Coronal radio sounding: Non-Gaussian turbulence in the source regions of slow and fast solar wind
Pätzold, M.; Bird, M. K.; Karl, J.
Structure functions of arbitrary order are analyzed using differential phase scintillation data obtained during the fourth solar conjunction of the Ulysses spacecraft in February-March 1995. The scaling features of these structure functions clearly discriminate between electron density fluctuations observed in coronal holes versus coronal streamer…
Spectroscopic observations of the interacting binary BY Crucis.
Waelkens, C.; Daems, K.
We present multi-wavelength spectroscopic data of the 106 day period interacting binary BY Crucis (Daems et al., 1997A&A...317..823D). The system consist of an early F-type supergiant that fills its Roche lobe and a more massive companion, hidden in a thick accretion disc. In the far-UV spectra (from 1200Å to 1950Å), strong emission lines of h…
The Potsdam contribution to the extragalactic link of the HIPPARCOS pr oper motion system
Scholz, R. -D.; Schilbach, E.; Hirte, S.
Absolute proper motions of 360 Hipparcos stars in 24 fields well distributed over the northern sky were derived from measurements of photographic plates taken mainly with the Tautenburg Schmidt telescope (134/200/400 cm). In each field (about 10 square degrees) a large number of galaxies was used to link the proper motions to the extragalactic ref…
Dust Features of Visually Bright AGB Variables as Seen by ISO and IRAS
Loidl, Rita; Hron, Josef; Kerschbaum, Franz
ISO-SWS spectra of two Mira variables (R Cas and T Dra), taken at two different pulsational phases, are presented. We describe the reduction of the data and the encountered problems. The dust features observed by ISO at different phases and with the Low Resolution Spectrometer of IRAS are compared. We briefly discuss the results in terms of curren…
First Energetic Particle Events Observed by the ERNE Instrument
Laitinen, T.; Vainio, R.; Valtonen, E. +6 more
The energetic particle instrument ERNE on-board SOHO started its observations on December 15, 1995. The low-energy sensor of ERNE, LED, is capable of measuring particles in the energy range from 1 to 10 MeV nucl-1. From the beginning of the year 1996 until May 22, 1996, LED-observations included four energetic particle events above thre…
Galactic Cosmic Ray Confinement Time: Ulysses HET Measurements of the Secondary Radio - Nuclide 10Be
Connell, J.
Low energy charged particles in the high latitude heliosphere
Lanzerotti, L. J.; Armstrong, T. P.; Gold, R. E. +3 more
Low energy ion and electron measurements made over the south and north polar regions of the sun by the HI-SCALE instrument on the Ulysses spacecraft during its solar minimum polar passages are summarized. The polar flux levels were considerably reduced in comparison to fluxes in the vicinity of the heliospheric current sheet. Flux variations with …
The Bonn contribution to the extragalactic link of the HIPPARCOS proper motion system.
Tucholke, H. -J.; Brosche, P.; Odenkirchen, M.
In order to calibrate the proper motions of the Hipparcos astrometry satellite, our group has measured accurate absolute proper motions of Hipparcos stars in small fields around optically bright extragalactic radio sources or bright galaxies with star-like features. In addition, we also use fields where relative proper motions are calibrated by me…
Astrometric positions of stars with high proper motions in the Southern Hemisphere
Rousseau, J. M.; Perie, J. P.
Several stars with large proper motions, cited by W.J. Luyten, were included in the preliminary programme for the HIPPARCOS mission. When performing preparatory measurements of plates, difficulties were encountered in identifying certain of these stars when relying only on published coordinates. We have taken advantage of this work which relates t…