Gould's Belt

TL;DR

This paper investigates various models of the Gould's Belt's expansion and origin, comparing them with observed velocity patterns, and suggests it may result from shell collisions or instabilities in galactic gas flows.

Contribution

The study evaluates multiple expansion models and proposes a possible origin of the Gould's Belt linked to galactic gas flow instabilities and shell interactions.

Findings

No definitive expansion time; ranges from 30 to 100 Myr.

Models struggle to explain the belt's inclination.

High velocity cloud impact is a possible but unconfirmed explanation.

Abstract

The local velocity patterns of star forming regions, young OB stars, nearby OB associations, atomic and molecular gas are confronted with models of an expanding region. We test free expansion from a point or from a ring, expanding 2D shell, and expanding 3D belt with abrupt or gradual energy injection snow-plowing the ambient medium with or without the drag forces including fragmentation and porosity of the medium. There is no agreement on the expansion time, which varies from 30 - 100 Myr. The inclination of the Gould belt is not explained by the above models of expansion. An oblique impact of a high velocity cloud may explain it, but the observed velocity pattern is difficult to reproduce. The Gould's belt may be one of the many structures resulting from shell-shell collisions in the galactic plane. The origin of the Gould's belt may be connected to instabilities in the curling gas flows downstream from the Galaxy spiral arms, forming ISM clouds and star formation complexes.