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Prospects in astrometry and orbital determination of minor bodies

Carpino, M.

The astrometry of asteroids and comets is undergoing a significant progress, both in accuracy and number of observations, as a consequence of the introduction of CCD devices and the availability of stellar catalogues dense enough to cope with CCD relatively small fields of view. Further, substantial progress in accuracy is expected from the availa…

Determination of highly precise proper motions for 32 Hipparcos stars from photographic plates.

Wang, S.; Wang, J.; Jin, W. +1 more

The authors have reduced 70 exposures on 32 photographic plates taken in four areas of the sky around the radio source 0316+413, the galaxy NGC 7302, the Pleiades astrometric standard region, and so on with the 40-cm astrographic refractor at SheShan (Zô-Sé) Station of the Shanghai Observatory. Using the PPM catalogue as the initial reference cata…

Determination of T(eff) and log G for A0 type stars and its impact on the interpretation of the HR diagram with the HIPPARCOS results

Gomez, A.; Gerbaldi, M.; Faraggiana, R. +3 more

The determination of the "Fundamental Parameters" T(eff) and log g for a set of dwarf A0-type stars is discussed in terms of consistency when comparing these values determined through different methods. The position of these stars in the HR diagram are discussed, taking into account the HIPPARCOS data. A large number of binary stars with component…

Atmospheric parameters and abundances of lambda Bootis stars

Heiter, U.

The results of the abundance analyses of six lambda Bootis stars are presented. For three stars, the impact of individual ODFs and various treatments of convection in the calculations of the model atmospheres are investigated.

ISO-SWS Spectra of Carbon Stars: Molecular Features and a Comparison with Models

Jørgensen, U. G.; Hron, J.; Kerschbaum, F. +1 more

Mesures d'etoiles doubles effectuees a la lunette de 50 CM de l'Observatoire de Nice (2({) e. Measures of visual double stars made with the 50 CM refractor at the Nice Observatory (2^{nd

Thorel, J. -C.

66 measures of 38 visual double stars made at the Observatoire de la Cote d'Azur, at Nice, in september et december 1997, with the 50 cm equatorial refractor equipped with filar micrometer and electronic recording device. Observation programmes of stars suspected double and new binaries discovered by Hipparcos, and measures of double stars which h…

Simulation and methods for the data analysis of the hydrogen-deuterium-absorption-cell-experiment on Cassini

Reulke, R.; Warlich, K.; Jahn, H.

The Hydrogen-Deuterium-Absorption-Cell (HDAC) will be flown as part of the UltraViolet Imaging Spectrograph on the Cassini mission with the objective to determine the deuterium-to-hydrogen (D/H) ratio in the exosphere of Titan. The HDAC is a photometer designed to measure separately the H and D resonant scattered solar Lyman alpha radiation. A non…

The solar wind alpha-particle content as a clue for the origin of slow flows

Bavassano, B.; Pietropaolo, E.; Bruno, R.

Some aspects of the variation of the alpha-particle abundance in the solar wind are studied using Ulysses data. We focus on the first mid-latitude phase of the mission, when the spacecraft intermittently enters the fast high-latitude wind, and on the region around the first perihelion passage, when low-latitude wind in conditions of low solar acti…

Verifying the accuracy of the third interplanetary network: localization of the bursting pulsar GRO J1744-28 by triangulation

Cline, T.; Hurley, K.; Kouveliotou, C. +8 more

The bursting pulsar GRO J1744-28 is the first repeating source of intense bursts whose position is accurately known, which has become active since the establishment of the third interplanetary network. We show how observations of this object with Ulysses and BATSE can be used to verify many aspects of the triangulation method. Analysis of the prel…

Cassini radar : system concept and simulation results

Orosei, R.; Picardi, G.; Seu, R. +1 more

The Cassini mission is an international venture, involving NASA, the European Space Agency (ESA) and the Italian Space Agency (ASI), for the investigation of the Saturn system and, in particular, Titan. The Cassini radar will be able to see through Titan's thick, optically opaque atmosphere, allowing us to better understand the composition and the…