Preparing for the VLTI: A Search for Pre-Main Sequence Spectroscopic Binaries

The most fundamental parameter of a star is its mass. For low mass pre-main sequence (pms) stars this parameter is practically always derived by comparing the location of the star in the Hertzsprung-Russell diagram with theoretically calculated evolutionary tracks. In order to really test the tracks, determination of the masses of a number of pms-stars are necessary. Up to now, masses could only be derived for a few individual cases. In the near future the VLTI will allow us to determine the masses of many pms-stars with high accuracy. In order to prepare for the VLTI-observation, we have begun a survey for long period pms-spectroscopic binaries that should be resolvable with the VLTI. We find that 8% of the stars surveyed show significant radial-velocity variations, and are thus most likely spectroscopic binaries. In addition to these, 6% of the targets are double-lined spectroscopic binaries. The second aim of the survey is to find also all eclipsing binaries amongst these stars, and we have in fact found a highly promising candidate. An eclipsing binary announced previously by other authors turned out to be a spotted star.