Turbulence: A Probe of the Dynamics and Physics of the Magellanic Stream

TL;DR

This study analyzes HI observations of the Magellanic Stream's tip, revealing large-scale turbulence and complex structures, and uses these findings to infer physical properties and constraints on the stream's orientation and density.

Contribution

It provides the first detailed analysis of turbulence in the Magellanic Stream using high-resolution HI data, linking turbulence characteristics to the stream's dynamics and physical conditions.

Findings

Detection of large-scale turbulence with a 40 kpc size

Estimated turbulent velocity of about 15 km/s

Turbulence decay timescale of approximately 3 Gyr

Abstract

A recent paper by Stanimirovic etal (2008) presents quit interesting results from HI observations of the Magellanic Stream (MS) tip. The high spatial resolution of the data reveals rich and complex morphological and kinematic structures; notably four coherent HI substreams extending over angular size of about 20 deg were found. We use the position-velocity images of Stanimirovic etal (2008) to derive spatial power spectra for the velocity residuals. These, indicate the presence of a large scale turbulence with size comparable to that of the streams themselves. The turbulent velocity on the largest scale is estimated to be about 15 km/s . Adopting, a distance of 120 kpc, implies a turbulent largest scale of 40 kpc and timescale for decay of about 3 Gyr. For a turbulence with scale that large, the natural energy source is the tidal interaction between the Magellanic Clouds, and between them and the Milky Way galaxy. The shape of derived turbulence spectrum is used here to obtain constraints on the inclination of the streams and on the density of the emitting neutral hydrogen.