The Radcliffe Wave as the gas spine of the Orion Arm

TL;DR

The paper investigates the Radcliffe Wave's role as the gas backbone of the Orion Arm, revealing its spatial relationship with young stars and star-forming regions to understand Galactic structure and star formation processes.

Contribution

It provides the first detailed analysis linking the Radcliffe Wave to the Orion Arm using Gaia data and dust maps, proposing it as the primary gas reservoir for star formation in this region.

Findings

Massive stars and clusters are located downstream of the Radcliffe Wave.

The Radcliffe Wave likely serves as the gas reservoir of the Orion (Local) Arm.

Spatial offset patterns resemble those seen in external galaxy spiral arms.

Abstract

The Radcliffe Wave is a $\sim3$ kpc long coherent gas structure containing most of the star-forming complexes near the Sun. In this Letter we aim to find a Galactic context for the Radcliffe Wave by looking into a possible relationship between the gas structure and the Orion (Local) Arm. We use catalogs of massive stars and young open clusters based on \textit{Gaia} EDR3 astrometry, in conjunction with kiloparsec-scale 3D dust maps, to investigate the Galactic \textit{XY} spatial distributions of gas and young stars. We find a quasi-parallel offset between the luminous blue stars and the Radcliffe Wave, in that massive stars and clusters are found essentially inside and downstream from the Radcliffe Wave. We examine this offset in the context of color gradients observed in the spiral arms of external galaxies, where the interplay between density wave theory, spiral shocks, and triggered star formation has been used to interpret this particular arrangement of gas/dust and OB stars, and outline other potential explanations as well. We hypothesize that the Radcliffe Wave constitutes the gas reservoir of the Orion (Local) Arm, and presents itself as a prime laboratory to study the interface between Galactic structure, the formation of molecular clouds in the Milky Way, and star formation.