ASTROMETRIC INDICATIONS OF BROWN DWARFS BASED ON HIPPARCOS DATA H.-H. Bernstein

In order to investigate the standard star solutions of the astrometric parameter determination in the FAST consortium, I developed an algorithm for the detection of astrometric binaries. The application of this algorithm was concentrated on those objects, where the Ø 2 -test of the astrometric parameter estimation using a single star model was not satisfactory. This method will be outlined in this paper. It is shown, that the accuracy of the Hipparcos observations allows the detection of brown dwarfs as a component of an astrometric binary. A systematic search of low mass companions among the M and K stars in the solar neighbourhood delivered six candidates possibly orbited by a brown dwarf, including Gliese 433. Key words: space astrometry; astrometric binaries; low mass companions. 1. INTRODUCTION Searching for low mass companions like brown dwarfs seems to be one of the most exciting tasks in astronomy nowadays. This paper outlines how Hipparcos is able to contribute to this subje..