Name/Affiliation: Sebastian Daemgen (University of Toronto)
Disk Evolution in T Tauri Binary Systems
Binaries are the most common outcome of star formation. Accordingly, most protoplanetary disks are born and evolve under the influence of a nearby stellar companion. Among the expected consequences of the resulting disk truncation, stirring, and irradiation are a reduced disk lifetime in close binaries and a predominance of circumprimary over circumsecondary material with possible consequences for, e.g., planet formation around either component. Observational constraints are currently sparse due to the high angular resolution required to determine the evolutionary states of individual binary components and their disks, in particular in the interesting separation range between ~10 and 100AU where the expected effects are most pronounced. In the largest coherent study of its kind we use high-angular resolution near-infrared spectroscopy and photometry to measure the presence of accretion and hot circumstellar dust around the individual components of 52 multiple stars with separations between ~20 and 800 AU in the Orion Nebula Cluster and Chamaeleon I star-forming regions. We confirm evidence from spatially unresolved studies that the overall disk frequency is lower in binaries with <100 AU separation. The inferred mass accretion rates, however, appear to be indistinguishable from those of single stars. In addition, we see evidence that circumsecondary disks live on average shorter than their circumprimary counterparts and find an unexpected deficit of wide binaries with two accreting components. Together with information about the presence of cold outer dust around binary components from recent sub-/mm studies, we attempt to draw a coherent picture of protoplanetary disk evolution in binaries that is consistent with the observed disk properties and planet frequencies.