Preferential alignment of Class 0, Class I protostellar disks in multiple systems across nine nearby molecular clouds
arXiv:2607.14294
The study examines the orientations of protostellar disks in 512 Class 0, Class I, and flat‑spectrum sources across nine nearby molecular clouds, finding that disks in binary and higher‑order multiple systems are preferentially aligned up to separations of ~6000 au, which challenges models that rely solely on turbulent fragmentation.
Abstract
Protostellar disk orientations in multiple systems provide critical insights into the primary mechanisms that govern the formation of multiple-star systems, their subsequent dynamical evolution, and their impact on planet-forming disks. We present a disk alignment study of 512 Class 0, Class I, and flat-spectrum protostars across nine nearby molecular clouds within 500 pc, utilizing data from the CAMPOS and VANDAM surveys. Our sample includes 74 binaries and 31 high-order multiple systems. We find that multiple systems with projected pair separations up to 6000 au exhibit preferential disk alignment with respect to each other across all evolutionary classes, deviating significantly from the random distribution predicted by turbulent fragmentation models. This suggests that the formation of multiple systems cannot be explained by turbulent fragmentation alone. Disk alignment on scales of a few thousand au is also difficult to explain by disk fragmentation as the dominant origin. We further find that the degree of nearest-neighbor disk alignment in higher-order multiples is comparable to that in binaries. Finally, we identify a significant deficit of flat-spectrum protostellar disks in high-order multiple systems as compared to younger Class 0 and Class I phases. The decline is consistent with rapid dynamical evolution, in which most higher-order systems dissolve by the end of the Class I phase.
39 pages, 25 figures, 4 tables. Accepted by A&A 2026.7.15