A Galactic-scale gas wave in the Solar Neighborhood (2001.08748v1)

Abstract: For the past 150 years, the prevailing view of the local Interstellar Medium (ISM) was based on a peculiarity known as the Gould's Belt, an expanding ring of young stars, gas, and dust, tilted about 20$^\circ$ to the Galactic plane. Still, the physical relation between local gas clouds has remained practically unknown because the distance accuracy to clouds is of the same order or larger than their sizes. With the advent of large photometric surveys and the Gaia satellite astrometric survey this situation has changed. Here we report the 3-D structure of all local cloud complexes. We find a narrow and coherent 2.7 kpc arrangement of dense gas in the Solar neighborhood that contains many of the clouds thought to be associated with the Gould Belt. This finding is inconsistent with the notion that these clouds are part of a ring, disputing the Gould Belt model. The new structure comprises the majority of nearby star-forming regions, has an aspect ratio of about 1:20, and contains about 3 million solar masses of gas. Remarkably, the new structure appears to be undulating and its 3-D distribution is well described by a damped sinusoidal wave on the plane of the Milky Way, with an average period of about 2 kpc and a maximum amplitude of about 160 pc. Our results represent a first step in the revision of the local gas distribution and Galactic structure and offer a new, broader context to studies on the transformation of molecular gas into stars.

• The paper identifies the Radcliffe Wave as a coherent 2.7 kpc structure of dense molecular gas that overturns traditional views of Gould’s Belt.
• The paper employs accurate Gaia distance measurements along 380 lines of sight to map the three-dimensional damped sinusoidal gas distribution.
• The paper suggests that Galactic dynamics, not local stellar feedback, shape this 3-million-solar-mass feature, prompting a reevaluation of interstellar structures.

A Galactic-scale Gas Wave in the Solar Neighborhood

This paper presents a detailed investigation into the three-dimensional organization of molecular gas clouds within the local interstellar medium (ISM), challenging the long-standing concept of Gould's Belt. The researchers utilized comprehensive distance measurements facilitated by the Gaia satellite and large photometric surveys to analyze local cloud complexes, ultimately revealing a new structural configuration termed the Radcliffe Wave.

The research findings indicate a narrow, coherent arrangement of dense gas extending approximately 2.7 kpc within the Solar neighborhood. This arrangement encompasses a significant portion of nearby star-forming regions and contradicts the notion of Gould's Belt as an expanding ring. The structure has a mass on the order of 3 million solar masses, an aspect ratio of approximately 1:20, and its distribution follows a damped sinusoidal wave pattern with an average period of about 2 kpc and a maximum amplitude of approximately 160 parsecs.

The analysis involved meticulously deriving accurate distances for 380 lines of sight, aimed at both known clouds and potential connections of tenuous gas. This approach enabled the identification of a spatially and kinematically coherent structure, confirming the presence of the Radcliffe Wave. The structure's kinematic coherence is supported by the observed velocities of young stellar objects, suggesting a coordinated movement within the local galactic disk.

The Radcliffe Wave's discovery necessitates a reevaluation of Galactic architecture in the Solar neighborhood. Its identification suggests that what was previously perceived as Gould's Belt is more accurately a superposition of linear cloud complexes observable against the sky. The paper further proposes that this projection effect explains the Gould Belt's inclined orientation.

The origin of the Radcliffe Wave remains speculative. Its large size and straightness imply that it is not the result of local stellar feedback, but rather a consequence of broader Galactic dynamics, possibly related to gravitational settling or shock fronts within spiral arms. Beyond uncovering a novel Galactic structure, these results have substantial implications for understanding molecular cloud formation and the processes governing star formation.

Future research is poised to refine these findings, particularly through the kinematic paper of the Radcliffe Wave, which could elucidate the roles of gravity, feedback processes, and magnetic fields in star genesis. The paper calls for a comprehensive reassessment of the interplay between local molecular clouds, potentially reshaping a host of related astrophysical phenomena theories.

Overall, the research offers a significant revision to the understanding of interstellar structure in the Solar vicinity, paving the way for future studies to explore the intricacies of our Galaxy's gas distribution beyond the classical models.