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Preliminary retrieval of solar wind latitude distribution from Solar Wind Anisotropies/SOHO observations
Schmidt, W.; Quemerais, E.; Bertaux, J. -L. +5 more
The Solar Wind Anisotropies (SWAN) instrument on board the SOHO spacecraft measures Lyman alpha radiation emanating mainly from neutral hydrogen gas in the solar neighborhood. This gas is part of the local interstellar cloud in which the Sun and the heliosphere are immersed. Measurements of Lyman alpha can be used to infer the local cloud characte…
Heating and acceleration of minor ions in the solar wind
McKenzie, J. F.; Czechowski, A.; Axford, W. I. +1 more
We make use of the results of a one-ion model of McKenzie et al. (1997) to obtain the critical solution describing the acceleration of a two-ion solar wind. The model includes preferential heating of the heavy ion species and the temperature anisotropy expected if the heating is predominantly due to ion-cyclotron damping. The relationship of the m…
A ring of organic molecules around HD 97300
Prusti, T.; Siebenmorgen, R.; Natta, A. +1 more
This paper presents spectro-photometric images of the pre-main-sequence Herbig AeBe star HD 97300 in the mid-IR obtained with ISOCAM on board of ISO. The images show extended emission, an elliptical ring structure of size about 0.045x0.03 pc as well as two peaks of emission, separated by about 3arcsec (240 AU). One of the two peaks coincides with …
Behaviour of calcium abundance in Am-Fm stars with evolution
North, P.; Kunzli, M.
Calcium abundance in the atmosphere of Am stars is examined as a function of their evolutionary state within the main sequence. New spectroscopic abundances as well as abundances obtained photometrically by Guthrie (1987) are used, since they are mutually quite consistent. The main result of this work is that, contrary to earlier suggestions, calc…
Deduced spectrum of interacting protons accelerated after the impulsive phase of the 15 June 1991 solar flare
Kocharov, L.; Rank, G.; Nieminen, P. +6 more
In June 1991 the Sun produced a famous series of six powerful flares. For the solar eruption on 15 June 1991 there exists a rich set of measurements, including in particular >~mma-ray and neutron observations of the COMPTEL instrument on board the COMPTON Gamma Ray Observatory (CGRO) satellite. The >~mma-ray and neutron emissions indicate pr…
HIPPARCOS positioning of Geminga: how and why
Caraveo, P. A.; Bignami, G. F.; Makarov, V. V. +4 more
Accuracy in the absolute position in the sky is one of the limiting factors for pulsar timing, and timing parameters have a direct impact on the understanding of the physics of Isolated Neutron Stars (INS). We report here on a high-accuracy measurement of the optical position of Geminga (mv=25.5), the only known radio-quiet INS. The pro…
Latitudinal Variation of Solar Subsurface Rotation Inferred from p-Mode Frequency Splittings Measured with SOI-MDI and GONG
Kosovichev, A. G.; Birch, A. C.
Analysis of p-mode frequency splittings as measured by the Solar Oscillations Investigation-Michelson Doppler Imager (SOI-MDI) on board the Solar and Heliospheric Observatory and the ground-based Global Oscillations Network Group (GONG) experiment reveal that the symmetric component of the solar rotation rate in the upper 4% by radius and closer t…
The D/H ratio at z=0.7 toward Q 1718+4807
Takahara, Fumio; Levshakov, Sergei A.; Kegel, Wilhelm H.
The apparent discrepancy between low and high D abundances derived from QSO spectra may be caused by spatial correlations in the stochastic velocity field. If one accounts for such correlations, one finds good agreement between different observations and the theoretical predictions for standard big bang nucleosynthesis (SBBN). In particular, we sh…
The Cosmic-Ray Radioactive Nuclide 36Cl and Its Propagation in the Galaxy
Simpson, J. A.; Connell, J. J.; DuVernois, M. A.
Radioactive 36Cl has been resolved from 35Cl and 37Cl for the first time in the cosmic radiation with measurements obtained from the high-resolution High-Energy Telescope (HET) carried on the NASA-ESA Ulysses spacecraft. Within the framework of a homogeneous propagation model wherein all 36Cl is of spall…
Wind Velocity Variations in the Luminous Blue Variable-Type Erupting Star of the Wolf-Rayet Binary HD 5980
Koenigsberger, G.; Auer, L. H.; Georgiev, L. +1 more
We present the wind velocity and UV luminosity variations in the Wolf-Rayet system HD 5980 obtained over a time span during which one of the stars of the system was transformed into a luminous blue variable and underwent an eruption. We are able to separate the velocity components of the two stars in the system: a stable velocity component at -170…