Search Publications

Separation rate of the magnetic field lines observed by ULYSSES at high latitude

Balogh, A.; Erdös, G.; Kóta, J.

Ulysses has observed enhanced magnetic field fluctuations embedded in the fast solar wind originating from the high latitude coronal hole. These fluctuations proved to affect charged particle transport significantly. In this paper we apply a new method to determine the magnetic field line mixing from the actually measured magnetic field.

Ly alpha Constraints on the Nature of the X-Ray--absorbing Medium in Cooling Flow Clusters

Laor, Ari

X-ray spectra of a significant fraction of cooling flow (CF) clusters of galaxies indicate the presence of large columns of ``cold'' absorbing material. The physical nature of the absorbing medium remains a mystery. Searches for H I in this medium using the 21 cm hyperfine structure line yielded null results in most cases. The Lyα absorption cross…

Elemental abundances in the Hg-Mn star γ Corvi.

Houziaux, L.; Fremat, Y.

Spectral data obtained at ESO, Observatoire de Haute-Provence and with the IUE covering the 120-910nm spectral range allowed us to determine the abundances of 21 elements in the atmosphere of the moderately fast rotating Hg-Mn star γ Corvi. We find that helium, carbon, nitrogen, magnesium, aluminium, silicium, sulfur, chromium, iron and nickel are…

M VIII Diagnostic Line Ratios in SKYLAB Solar Observations

Doyle, J. G.; Keenan, F. P.; Widing, K. G. +4 more

Recent calculations of Mgviii electron and proton impact excitations rates are used to derive theoretical electron temperature (T_e)- and density (N_e)-sensitive emission line ratios involving transitions in the 315-782 Å wavelength range. Some of these ratios are presented in the form of ratio-ratio diagrams, which should in p…

Using the Earth orientation parameters to link the HIPPARCOS and VLBI reference frames.

Pesek, I.; Vondrak, J.; Ron, C.

One of the methods, used to link the free Hipparcos reference system to the conventional extragalactic reference system, is the indirect method using the rapidly rotating terrestrial reference system as an intermediary. We solve the Earth orientation parameters, referred to the preliminary Hipparcos reference frame H37C, from the observations made…

ISO-SWS Spectra of AGB Stars

Waters, L. B. F. M.; Justtanont, K.; Yamamura, I. +1 more

In this contribution, we present a few highlights of the guaranteed time program to observe AGB stars with differing chemical compositions and mass loss rates using ISO¹ SWS. We briefly discuss C₂H₂ absorption in C-stars and O-rich stars with the 13 µm dust emission.

The eclipsing AM Herculis binary V2301 Ophiuchi. I. ROSAT & IUE observations.

Burwitz, V.; Beuermann, K.; de Martino, D. +2 more

We present X-ray and UV observations of the unique eclipsing cataclysmic variable V2301 Oph (1H1752+081). The X-ray eclipse of the primary star is total and corresponds in phase with the optical eclipse of the white dwarf. The X-ray light curve shows a quasi-sinusoidal orbital ``hump'' typical of AM Her systems. The orbital phase at which the hump…

The winds of hot close binaries. Paper 3: HD 159176

Stickland, D. J.; Pachoulakis, I.; Koch, R. H. +1 more

NICMOS/HST Post-Perihelion Images of Comet Hale-Bopp in Outburst

Spinrad, H.; Schneider, G.; McCarthy, D. +5 more

Near-infrared images of comet Hale-Bopp (C/1995 O1) were obtained from NICMOS/HST on UT August 27–28, 1997, when the comet emerged from the 50 degree solar elongation limit at 2.99 AU from Earth. Diffraction-limited images were obtained with camera 2 filters centered at 1.87, 1.90, 2.04 and 2.22 µm with ∼0.2″ resolution (0.076″/pixel; 165 km…

The Effects of Coronal Mass Ejections on Galactic Cosmic Rays in the High Latitude Heliosphere: Observations from Ulysses' First Orbit

Kunow, H.; Bothmer, V.; Wibberenz, G. +2 more

During its first solar orbit, the Ulysses spacecraft detected several coronal mass ejections (CMEs) at high heliographic latitudes. The authors present first observations on the effects of these high latitude CMEs on galactic cosmic rays (GCRs) using measurements from the Kiel Electron Telescope (KET) which is part of the Cosmic Ray and Solar Part…