Simon, Michal 9417191 In the nearby Taurus and Ophiuchus star forming regions, most of the stars are formed in multiple systems. Binary formation appears to be the dominant mode of star formation. The first goal of this research is to investigate whether this result is a peculiarity of either the class of young stars observed or of the star forming region. Very large, new samples of X-Ray selected young stars in the Orion OB association and Corona Australis will be surveyed for multiplicity. The second goal is to measure the most fundamental stellar parameter, the mass, in at least some of the young star binaries. High resolution IR spectroscopy offers the possibility of identifying low mass companions that elude detection in the visible. The third goal is to study the early evolution of binaries and their inner disks by angularly resolved IR spectroscopy. ***
