Close pre–main-sequence binary stars are expected to clear central holes in their protoplanetary disks , but the extent to which material can flow from the circumbinary disk across the gap onto the individual circumstellar disks has been unclear .
In binaries with eccentric orbits , periodic perturbation of the outer disk is predicted to induce mass flow across the gap , resulting in accretion that varies with the binary period .
This accretion may manifest itself observationally as periodic changes in luminosity .
Here we present a search for such periodic accretion in the pre–main-sequence spectroscopic binary UZ Tau E. We present BVRI photometry spanning three years ; we find that the brightness of UZ Tau E is clearly periodic , with a best-fit period of 19.16 \pm 0.04 days .
This is consistent with the spectroscopic binary period of 19.13 days , refined here from analysis of new and existing radial velocity data .
The brightness of UZ Tau E shows significant random variability , but the overall periodic pattern is a broad peak in enhanced brightness , spanning more than half the binary orbital period .
The variability of the H \alpha line is not as clearly periodic , but given the sparseness of the data , some periodic component is not ruled out .
The photometric variations are in good agreement with predictions from simulations of binaries with orbital parameters similar to those of UZ Tau E , suggesting that periodic accretion does occur from circumbinary disks , replenishing the inner circumstellar disks and possibly extending the timescale over which they might form planets .