Requiem for a belt: A spatial and kinematical reinterpretation of Gould's Belt in light of Gaia

TL;DR

This study uses Gaia DR3 data to reevaluate Gould's Belt, revealing it as a transient alignment of star clusters rather than a coherent physical structure, shaped by local star formation and observational effects.

Contribution

The paper provides a new interpretation of Gould's Belt as a transient asterism, challenging the traditional view of it as a unified, expanding ring.

Findings

Gould's Belt is not a single physical structure but a superposition of cluster groups.

The apparent inclination is explained by the Radcliffe Wave's oscillatory pattern.

The kinematic features can be reproduced by known cluster motions and solar reflex effects.

Abstract

We reassess the long-standing idea of Gould's Belt using Gaia DR3 for a sample of young massive stars and nearby young clusters. The structure surrounding the Sun, often interpreted as an inclined, expanding, and rotating ring, emerges in our analysis as a transient alignment of a few cluster families rather than an individual, coherent dynamical feature. By combining the ALS III catalog of OB stars with a homogeneous sample of clusters younger than 70 Myr, and by tracing their motions in a realistic Galactic potential, we show that neither the spatial distribution nor the kinematics form a unified system. The inferred expansion, rotation, and bulk motion of the Belt can be reproduced by the superposition of the $\alpha$Per, Cr135, M6, and $\gamma$Vel cluster families and are further amplified by solar reflex motion and historical assumptions about the local standard of rest (LSR). The classic inclined geometry is largely explained by the oscillatory pattern of the Radcliffe Wave, which contributes a major arc of the supposed ring. Taken together, these results indicate that Gould's Belt is not a physical structure but a 3D asterism shaped by a complex local star formation history, observational biases, and projection effects.