Preparation of the HIPPARCOS Input Catalogue. Astrometric Programs for HIPPARCOS. Preliminary Astrometric Observations

Mass determination of astrometric binaries with Hipparcos

In a previous paper (Martin et al., 1997) we have shown that for double stars with orbital periods smaller than about 25 years, it was possible to determine from the Hipparcos data, the mass ratio B of the components or the difference between the mass and intensity ratios, β−B, provided the orbital elements of the relative orbit are available. Froman extensive literature search we have selected...

Application Possibilities for the Hipparcos Intermediate Astrometric Data

Examples of how and when to use the Hipparcos intermediate astrometric data are presented. It is shown how, through the use of the intermediate astrometric data, correlation problems can be properly accounted for. Applications are in general limited to three kinds: calibrations of a common parallax and proper motion for stars in clusters, calibrations of common luminosity properties for stars d...

Astrometric Control of the Inertiality of the Hipparcos Catalog

Screening the Hipparcos-based astrometric orbits of sub-stellar objects

The combination of Hipparcos astrometric data with the spectroscopic data of putative extrasolar planets seems to indicate that a significant fraction of these low-mass companions could be brown or M dwarfs (Han et al. 2001). We show that this is due to the adopted reduction procedure, and consequently that the Hipparcos data do not reject the planetary mass hypothesis in all but one cases. Add...

Unconstrained Astrometric Orbits for Hipparcos Stars with Stochastic Solutions

A considerable number of astrometric binaries whose positions on the sky do not obey the standard model of mean position, parallax, and linear proper motion were observed by the Hipparcos satellite. Some of them remain undiscovered, and their observational data have not been properly processed with the more adequate astrometric model that includes nonlinear orbital motion. We develop an automat...