Nature and origin of the Radcliffe wave

Determine the physical nature and origin of the Radcliffe wave, defined as an approximately 2.7 kpc-long, ~30°-inclined chain of molecular clouds in the Milky Way’s Local System that exhibits wave-like vertical displacements up to ~160 pc, and establish the mechanism responsible for its formation.

Background

The Radcliffe wave was identified as a narrow, nearly linear chain of molecular clouds extending roughly 2.7 kpc in the Galactic plane, with pronounced wave-like vertical displacements. Its discovery was enabled by precise distance estimates to nearby molecular clouds and has since been corroborated across multiple tracers, including dust, masers, young stars, and open clusters.

Several formation scenarios have been proposed in the literature, ranging from hydrodynamic instabilities (e.g., Kelvin–Helmholtz) and external impacts (e.g., dwarf galaxy or dark matter clumps) to feedback from supernovae and stellar winds during the creation of structures such as the Local Bubble and North Polar Spur. This review highlights that despite recent advances in kinematics and mapping, the fundamental physical nature and origin of the Radcliffe wave remain unresolved.