Binary star formation : Primary disks and secondary stars

Most intermediate mass, pre-main-sequence Herbig Ae/Be stars reside in binary systems. As they are young, the properties of these systems allow us to constrain how they form. We have investigated the formation of Herbig Ae/Be (HAe/Be) stars by assessing the relationship between HAe/Be binary systems and their circumstellar disks. To do this, we use linear spectropolarimetric observations over Hα to determine the orientation of circumstellar disks in HAe/Be binaries. We then employ the disk and binary data to investigate the relative orientation of the systems and their disks. We conclude that the orbital planes of HAe/Be binary systems and the disks around their primaries are likely to be co-planar. This is consistent with the notion that these systems, and perhaps massive stars, form via monolithic collapse and disk fragmentation.