We present 3D hydrodynamical models of the HD142527 protoplanetary disc, a bright and well studied disc that shows spirals and shadows in scattered light around a 100 au gas cavity, a large horseshoe dust structure in mm continuum emission, together with mysterious fast radial flows and streamers seen in gas kinematics. By considering several possible orbits consistent with the observed arc, we show that all of the main observational features can be explained by one mechanism -the interaction between the disc and the observed binary companion. We find that the spirals, shadows and horseshoe are only produced in the correct position angles by a companion on an inclined and eccentric orbit approaching periastron -the 'red' family from Lacour et al. (2016). Dust-gas simulations show radial and azimuthal concentration of dust around the cavity, consistent with the observed horseshoe. The success of this model in the HD142527 disc suggests other mm-bright transition discs showing cavities, spirals and dust asymmetries may also be explained by the interaction with central companions.

A succession of near-IR spectroscopic observations, taken nightly throughout an entire cycle of SS 433's orbit, reveal (i) the persistent signature of SS 433's accretion disc, having a rotation speed of ∼ 500 km s −1 (ii) the presence of the circumbinary disc recently discovered at optical wavelengths by Blundell, Bowler & Schmidtobreick (2008) and (iii) a much faster outflow than has previously been measured for the disc wind. From these, we find a much faster accretion disc wind than has noted before, with a terminal velocity of ∼1500 km s −1 . The increased wind terminal velocity results in a mass-loss rate of ∼10 −4 M ⊙ yr −1 . These, together with the newly (upwardly) determined masses for the components of the SS 433 system, result in an accurate diagnosis of the extent to which SS 433 has super-Eddington flows. Our observations imply that the size of the companion star is comparable with the semi-minor axis of the orbit which is given by √ 1 − e 2 40 R ⊙ , where e is the eccentricity. Our relatively high spectral resolution at these near-IR wavelengths has enabled us to deconstruct the different components that comprise the Brackett-γ line in this binary system, and their physical origins. With this line dominated throughout our series of observations by the disc wind, and the accretion disc itself being only a minority (∼15 per cent) contribution, we caution against use of the unresolved Brackett-γ line intensity as an "accretion signature" in X-ray binaries or microquasars in any quantitative way.

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