Survey of Orion Disks with ALMA (SODA)

Context. Observations of protoplanetary disks within multiple systems in nearby star-forming regions (SFRs) have shown that the presence of a neighboring object influences the evolution of dust in disks. However, the size of the available sample and the separation range covered are insufficient to fully understand the dust evolution in binary systems. Aims. The goal of this work, based on the Survey of Orion Disks with ALMA (SODA), is to comprehensively characterize the impact of stellar multiplicity on Class II disks in the L1641 and L1647 regions of Orion A (∼1–3 Myr). We characterized the protostellar multiplicity using the Atacama Large Millimeter/submillimeter Array (ALMA), the ESO-VISTA, and the Hubble Space Telescope. The resulting sample of 65 multiple systems is the largest catalog of wide binary systems to date (projected separation ≥1000 AU) and enables a more robust statistical characterization of the evolution and properties of protoplanetary disks. Methods. The disk population was observed in the continuum with ALMA at 225 GHz, with a median rms of 1.5 M⊕. We combined these data (resolution of ∼1.1″) with the ESO-VISTA near-infrared survey of the Orion A cloud (resolution of ∼0.7″). From this dataset, multiple-star systems were selected using an iterative inside-out search in projected separation (≥1000 AU). Results. We identify 61 binary systems, 3 triple systems, and 1 quadruple system. The separation range is between 1000 and 104 AU. The dust mass distributions inferred via the Kaplan-Meier estimator yield a median mass of 3.23−0.4+0.6 M⊕ for primary disks and 3.88−0.3+0.3 M⊕ for secondary disks. Conclusions. Combining our data with those available for the Lupus and Taurus disks, we identify a threshold separation of about 130 AU, beyond which the previously observed positive correlation between millimeter flux (and hence dust mass) and projected separation is lost. Recent theoretical models confirm that pre- and post-threshold systems are the result of different star formation processes, such as the fragmentation of gravitationally unstable circumstellar disks, the thermal fragmentation of infalling cores, or the turbulent fragmentation of molecular clouds. We can rule out the dependence on different SFRs: the cumulative mass distributions of multiples in SFRs of similar ages are statistically indistinguishable. This result strengthens the hypothesis that there is a universal initial mass distribution for disks.