The Influence of Tight Binaries on Protoplanetary Disk Masses

Abstract Binary systems are a common site of planet formation, despite the destructive effects of the binary on the disk. While surveys of planet-forming material have found diminished disk masses around binaries with medium separation (∼10–100 au), less is known about tight (<10 au) binaries, where a significant circumbinary disk may escape the disruptive dynamical effects of the binary. We survey over 100 spectroscopic binaries in the Orion A region with the Atacama Large Millimeter/submillimeter Array (ALMA), detecting significant continuum emission among 21 of them with disk masses ranging from 1 to 100 M ⊕ . We find evidence of systematically lower disk masses among the binary sample when compared to single-star surveys, which may reflect a diminished planet-forming potential around tight binaries. The infrared excess fraction among the binary sample is comparable to that of single stars, although the tight binaries without significant ALMA emission display tentative evidence of weaker 3–5 μ m excesses. The depletion of cold dust is difficult to explain by clearing alone, and the role of additional mechanisms needs to be explored. It may be the result of the formation pathway for these objects, systematic differences in intrinsic properties (e.g., opacity) or a bias in how the sample was constructed.