Combining our measurements with those in the literature, we find the binary fraction across these periods is a constant 5 per cent for primaries M 1 < 0.8 M ⊙, but then increases linearly with log M 1, demonstrating that natal discs around more massive protostars M 1 ≳ 1 M ⊙ become increasingly more prone to fragmentation. Excluding these white dwarfs, we determine the binary fraction of original A/F primaries to be 13.9 per cent ± 2.1 per cent over the same parameter space. While solar-type primaries exhibit a brown dwarf desert across short and intermediate periods, we find a small but statistically significant (2.6σ) population of extreme-mass-ratio companions ( q 0.1, we measure the binary fraction of current A/F primaries to be 15.4 per cent ± 1.4 per cent, though we find that a large fraction of the companions (21 per cent ± 6 per cent) 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. We parametrize the mass-ratio distribution using both inversion and Markov-Chain Monte Carlo forward-modelling techniques, and find it to be skewed towards low-mass companions, peaking at q ≈ 0.2. The method reaches down to small mass ratios q ≈ 0.02 and yields a highly homogeneous sample. 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. 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. The orbital parameters of binaries at intermediate periods (10 2–10 3 d) are difficult to measure with conventional methods and are very incomplete.
0 kommentar(er)
