Monday, March 6, 2017, 12:00pm to 1:00pm
Accretion Dynamics in Pre-Main Sequence Binaries
Protoplanetary disks are integral to the formation of low-mass stars and planets. A paradigm for the star-disk interaction has been extensively developed in the case of single stars. Most stars, however, form in binary or higher order systems where the distribution of disk material and mass flows are more complex. Short-period, pre-main sequence (pre-MS) binary stars can have up to three accretion disks: two circumstellar disks and a circumbinary disk separated by a dynamically cleared gap. Theory suggests that orbital motion may drive periodic accretion streams that flow from a circumbinary disk, across the gap, onto the circumstellar disks or stellar surfaces. Thus, accretion in pre-MS binaries is controlled not only by radiation, disk viscosity, and magnetic fields, but also by orbital dynamics. As part of an ongoing effort to characterize mass accretion in young binary systems, we test predictions of the binary accretion stream theory through multi-orbit, multi-color optical, time-series photometry. Our observations from LCO, SMARTS, WIYN 0.9m, and ARCSAT 0.5m provide detailed mass accretion rates as a function of orbital phase. The predicted phase and magnitude of enhanced accretion are highly dependent on the binary orbital parameters and as such, our campaign focuses on 9 pre-MS binaries of varying period and eccentricity. In this talk, I will present results highlighting the detection of consistent enhanced accretion events near the periastron passages of two eccentric binaries (DQ Tau and TWA 3A) and compare them to recent hydrodynamic models.