The orbital parameters of binaries at intermediate periods ( 10 ^ { 2 } – 10 ^ { 3 } d ) are difficult to measure with conventional methods and are very incomplete .
We have undertaken a new survey , applying our pulsation timing method to Kepler light curves of 2224 main-sequence A/F stars and found 341 non-eclipsing binaries .
We calculate the orbital parameters for 317 PB1 systems ( single-pulsator binaries ) and 24 PB2s ( double-pulsators ) , tripling the number of intermediate-mass binaries with full orbital solutions .
The method reaches down to small mass ratios q \approx 0.02 and yields a highly homogeneous sample .
We parametrize the mass-ratio distribution using both inversion and MCMC forward-modelling techniques , and find it to be skewed towards low-mass companions , peaking at q \approx 0.2 .
While solar-type primaries exhibit a brown dwarf desert across short and intermediate periods , we find a small but statistically significant ( 2.6 \sigma ) population of extreme-mass-ratio companions ( q < 0.1 ) to our intermediate-mass primaries .
Across periods of 100 – 1500 d and at q > 0.1 , we measure the binary fraction of current A/F primaries to be 15.4 % \pm 1.4 % , though we find that a large fraction of the companions ( 21 % \pm 6 % ) are white dwarfs in post-mass-transfer systems with primaries that are now blue stragglers , some of which are the progenitors of Type Ia supernovae , barium stars , symbiotics , and related phenomena .
Excluding these white dwarfs , we determine the binary fraction of original A/F primaries to be 13.9 % \pm 2.1 % over the same parameter space .
Combining our measurements with those in the literature , we find the binary fraction across these periods is a constant 5 % for primaries M _ { 1 } < 0.8 M _ { \odot } , but then increases linearly with \log M _ { 1 } , demonstrating that natal discs around more massive protostars M _ { 1 } \gtrsim 1 M _ { \odot } become increasingly more prone to fragmentation .
Finally , we find the eccentricity distribution of the main-sequence pairs to be much less eccentric than the thermal distribution .