Search Publications

A la découverte des comètes rasantes avec SOHO

Lamy, Hervé

Towards a fluid description of directional particle flux observations

Moussas, X.; Polygiannakis, J. M.; Alevizos, A.

We propose that, whenever directional flux measurements of a population of particles (e.g. solar energetic particles, cosmic rays, solar wind plasma) of well-defined energy resolution are available, new macroscopic fluid-like quantities (namely the energy dependent analog of density, mean velocity, anisotropic pressure, temperature and heat flux) …

Cold Ionospheric lons in the External Dayside Magnetosphere

Décréau, P. M. E.; Sauvaud, J. A.

CEP as a Source of Upstream Energetic Ions

Chen, Jiasheng; Fritz, Theodore A.

Primary research on a complex solar radio burst and its characteristics of microwave sources

Wang, Min; Wang, Kun-Shan; Xie, Rui-Xiang +4 more

A very complex outstanding solar radio burst was observed with the wide-band spectrometer of NAOC on October 19, 2001. This burst was characterized by a broader band (decameter to decimeter) burst followed by a more intense narrow-band burst at the lower frequencies (decimetric). NoRH (Nobeyama Radio Heliograph) observations about this event at 17…

Nebular abundances in southern symbiotic stars

Luna, G. J. M.; Costa, R. D. D.

We have calculated relative elemental abundances for a sample of 43 symbiotic stars. Helium abundances and the relative elemental abundances N/O, Ne/O were derived from new spectra collected in the optical range through low dispersion spectroscopy and from IUE low resolution spectra (SWP camera). The He ionic abundances were derived taking into ac…

Metrology of angles in astronomy

Kovalevsky, Jean

In astronomy, measurements of angles play a major role. After defining the units in use in astronomy, three methods of measuring angles are presented, with an application to the transit instrument. The interferometric techniques for measuring large angles are described in optical and radio wavelengths. Due to the atmospheric and mechanical limitat…

Some comments on the F ring-Prometheus-Pandora environment

Winter, O. C.; Giuliatti Winter, S. M.

The system formed by the F ring and two close satellites, Prometheus and Pandora, has been analysed since the time that Voyager visited the planet Saturn. During the ring plane crossing in 1995 the satellites were found in different positions as predicted by the Voyager data. Besides the mutual effects of Prometheus and Pandora, they are also dist…

The O VI and C III Lines at 1032 and 977 Å in Hyades F Stars

Robinson, Richard D.; Carpenter, Kenneth G.; Böhm-Vitense, Erika

We continue our investigations into the mechanisms heating the outer layers of cool dwarf stars. In this study we specifically seek to determine whether in the layers with temperatures around 250,000-300,000 K, in which the O VI lines are emitted, the temperatures are determined by heat conduction from the coronae or by the same processes that hea…