We present a large-scale , volume-limited companion survey of 245 late-K to mid-M ( K7-M6 ) dwarfs within 15 pc .
Infrared adaptive optics ( AO ) data were analysed from the Very Large Telescope , Subaru Telescope , Canada-France-Hawaii Telescope , and MMT Observatory to detect close companions to the sample from \sim 1 au to 100 au , while digitised wide-field archival plates were searched for wide companions from \sim 100 au to 10,000 au .
With sensitivity to the bottom of the main sequence over a separation range of 3 au to 10,000 au , multiple AO and wide-field epochs allow us to confirm candidates with common proper motions , minimize background contamination , and enable a measurement of comprehensive binary statistics .
We detected 65 co-moving stellar companions and find a companion star fraction of 23.5 \pm 3.2 per cent over the 3 au to 10,000 au separation range .
The companion separation distribution is observed to rise to a higher frequency at smaller separations , peaking at closer separations than measured for more massive primaries .
The mass ratio distribution across the q = 0.2 - 1.0 range is flat , similar to that of multiple systems with solar-type primaries .
The characterisation of binary and multiple star frequency for low-mass field stars can provide crucial comparisons with star forming environments and hold implications for the frequency and evolutionary histories of their associated disks and planets .