Context : The majority of the intermediate mass , pre-main-sequence Herbig Ae/Be stars reside in binary systems .
As these systems are young , their properties may contain an imprint of the star formation process at intermediate masses ( 2-15 { M _ { \odot } } ) .
However , these systems are generally spatially unresolved , making it difficult to probe their circumstellar environment to search for manifestations of their formation process , such as accretion disks .

Aims : Here we investigate the formation mechanism of Herbig Ae/Be ( HAe/Be ) binary systems by studying the relative orientation of their binary orbits and circumstellar disks .

Methods : We present linear spectropolarimetric observations of HAe/Be stars over the H \alpha line , which are used to determine the orientation of their circumstellar disks .
In conjunction with data from the literature , we obtain a sample of 20 binaries with known disk position angles ( PAs ) .
We subsequently compare our disk PA data to a model to investigate whether HAe/Be binary systems and their disks are co-planar .
Moreover , in the light of a relatively recent suggestion that some HAe/Be star spectropolarimetric signatures may not necessarily be related to circumstellar disks , we re-assess the relationship between spectropolarimetric signatures and disk PAs .
We do this by comparing spectropolarimetric and high spatial resolution observations of young stellar objects ( both HAe/Be and T Tauri stars ) .

Results : We find that spectropolarimetric observations of pre-main-sequence stars do indeed trace circumstellar disks .
This finding is significant above the 3 \sigma level .
In addition , our data are entirely consistent with the situation in which HAe/Be binary systems and circumstellar disks are co-planar , while random orientations can be rejected at the 2.2 \sigma level .

Conclusions : The conclusive alignment ( at more than 3 \sigma ) between the disk PAs derived from linear spectropolarimetry and high spatial resolution observations indicates that linear spectropolarimetry traces disks .
This in turn allows us to conclude that the orbital planes of HAe/Be binary systems and the disks around the primaries are likely to be co-planar , which is consistent with the notion that these systems form via monolithic collapse and subsequent disk fragmentation .