T Tauri Binaries in Orion: Evidence for Accelerated and Synchronized Disk Evolution

In order to trace the role of binarity for disk evolution and hence planet formation, we started the currently largest spatially resolved near-infrared photometric and spectroscopic study of the inner dust and accretion disks of the individual components of 27 visual, 100-400 AU binaries in the Orion Nebula Cluster (ONC). We study the frequency of Brackett-gamma (2.165 mu m) emitters to assess the frequency of accretion disk-bearing stars among the binaries of the ONC: only 34 +/- 9% of the binary components show signs of accretion and, hence, the presence of gaseous inner disks-less than the fraction of gas accretion disks among single stars of the ONC of similar to 50%. Additionally, we find a significant difference between binaries above and below 200 AU separation: no close systems with only one accreting component are found. The results suggest shortened disk lifetimes as well as synchronized disk evolution.