It is well known that circumbinary discs can allow the binary to evolve by acting as an angular momentum reservoir, but we have found that in the case of an asymmetric binary (non-equal mass and non-circular orbit), the young binary can cause strong precession in its disc causing interesting changes in accretion patterns. This is due to the non-Keplerian nature of the binary potential, and has strong implications both for long-term accretion variability and for how binary mass ratios can be set or changed during their young disc-accretion phase.
In Dunhill, Cuadra & Dougados (2015), we perform SPH simulations of the system HD104237. We see that the eccentric inner cavity of the disc formed through dynamical interactions with the binary begins to precess. This leads to a period change in the accretion pattern into the cavity through accretion streams, and onto the binary components. The movie below shows our simulation at four different times during its evolution, and clearly shows both the precession of the disc cavity and the changes in how the binary components accrete gas from the disc edge through streams.
We find that the binary component which sees the most accretion switches as the position angle of the cavity changes, allowing both components to accrete equally over time. This is in strong contrast to accretion onto circular binaries, where the secondary is always the primary accretor and the mass ratio is pushed closer to unity.