The Magellanic Stream: Circumnavigating the Galaxy

TL;DR

The paper reviews the Magellanic Stream's properties, origin, and dynamics, highlighting its significance for understanding galaxy interactions, gas accretion, and star formation in the Milky Way.

Contribution

It provides a comprehensive synthesis of current knowledge on the Stream's composition, physical state, origin scenarios, and its role in galactic evolution and interactions.

Findings

The Stream extends over 200 degrees on the sky.

It contains over a billion solar masses of gas.

Evidence supports tidal and ram-pressure interaction models.

Abstract

The Magellanic Clouds are surrounded by an extended network of gaseous structures. Chief among these is the Magellanic Stream, an interwoven tail of filaments trailing the Clouds in their orbit around the Milky Way. When considered in tandem with its Leading Arm, the Stream stretches over 200 degrees on the sky. Thought to represent the result of tidal interactions between the Clouds and ram-pressure forces exerted by the Galactic corona, its kinematic properties reflect the dynamical history of the closest pair of dwarf galaxies to the Milky Way. The Stream is a benchmark for hydrodynamical simulations of accreting gas and cloud/corona interactions. If the Stream survives these interactions and arrives safely in the Galactic disk, its cargo of over a billion solar masses of gas has the potential to maintain or elevate the Galactic star formation rate. In this article, we review the current state of knowledge of the Stream, including its chemical composition, physical conditions, origin, and fate. We also review the dynamics of the Magellanic System, including the proper motions and orbital history of the Large and Small Magellanic Clouds, the first-passage and second-passage scenarios, and the evidence for a Magellanic Group of galaxies.