Book contents
- Frontmatter
- Contents
- Preface
- Turbulence in the Interstellar Medium: a Retrospective Review
- Mechanism of Formation of Atmospheric Turbulence Relevant for Optical Astronomy
- Properties of Atomic Gas in Spiral Galaxies
- Turbulence in the Ionized Gas in Spiral Galaxies
- Probing Interstellar Turbulence in the Warm Ionized Medium using Emission Lines
- The Spectrum & Galactic Distribution of MicroTurbulence in Diffuse Ionized Gas
- Small Scale Structure and Turbulence in the Interstellar Medium
- What is the Reynolds Number of the Reynolds' Layer?
- Photoionized Gas in the Galactic Halo
- Turbulent Heating of the Diffuse Ionized Gas
- Cosmic Rays in Interstellar Turbulence
- Turbulence in Line-Driven Stellar Winds
- An Introduction to Compressible MHD Turbulence
- Turbulence in Atomic Hydrogen
- Supershells in Spiral Galaxies
- The Size Distribution of Superbubbles in the Interstellar Medium
- Large-Scale Motions in the ISM of Elliptical and Spiral Galaxies
- Vortical Motions Driven by Supernova Explosions
- The Intermittent Dissipation of Turbulence: is it Observed in the Interstellar Medium?
- Chemistry in Turbulent Flows
- Supersonic Turbulence in Giant Extragalactic HII Regions
- Turbulence in HII regions: New results
- Hypersonic Turbulence of H2O Masers
- Water Masers Tracing Alfvenic Turbulence and Magnetic Fields in W51 M and W49 N
- Turbulence in the Ursa Major cirrus cloud
- The Collisions of HVCs with a Magnetized Gaseous Disk
- The Initial Stellar Mass Function as a Statistical Sample of Turbulent Cloud Structure
- The Structure of Molecular Clouds: are they Fractal?
- Diagnosing Properties of Turbulent Flows from Spectral Line Observations of the Molecular Interstellar Medium
- Centroid Velocity Increments as a Probe of the Turbulent Velocity Field in Interstellar Molecular Clouds
- High-Resolution C18O Mapping Observations of Heiles' Cloud 2 – Statistical Properties of the Line Width –
- Observations of Magnetic Fields in Dense Interstellar Clouds: Implications for MHD Turbulence and Cloud Evolution
- The Density PDFs of Supersonic Random Flows
- Turbulence as an Organizing Agent in the ISM
- Turbulence and Magnetic Reconnection in the Interstellar Medium
- The Evolution of Self-Gravitating, Magnetized, Turbulent Clouds: Numerical Experiments
- Super–Alfvénic Turbulent Fragmentation in Molecular Clouds
- Decay Timescales of MHD Turbulence in Molecular Clouds
- Numerical Magnetohydrodynamic Studies of Turbulence and Star Formation
- Direct Numerical Simulations of Compressible Magnetohydrodynamical Turbulence
- Fragmentation in Molecular Clouds: The Formation of a Stellar Cluster
- Accretion Disk Turbulence
- List of participants
Turbulence as an Organizing Agent in the ISM
Published online by Cambridge University Press: 04 August 2010
- Frontmatter
- Contents
- Preface
- Turbulence in the Interstellar Medium: a Retrospective Review
- Mechanism of Formation of Atmospheric Turbulence Relevant for Optical Astronomy
- Properties of Atomic Gas in Spiral Galaxies
- Turbulence in the Ionized Gas in Spiral Galaxies
- Probing Interstellar Turbulence in the Warm Ionized Medium using Emission Lines
- The Spectrum & Galactic Distribution of MicroTurbulence in Diffuse Ionized Gas
- Small Scale Structure and Turbulence in the Interstellar Medium
- What is the Reynolds Number of the Reynolds' Layer?
- Photoionized Gas in the Galactic Halo
- Turbulent Heating of the Diffuse Ionized Gas
- Cosmic Rays in Interstellar Turbulence
- Turbulence in Line-Driven Stellar Winds
- An Introduction to Compressible MHD Turbulence
- Turbulence in Atomic Hydrogen
- Supershells in Spiral Galaxies
- The Size Distribution of Superbubbles in the Interstellar Medium
- Large-Scale Motions in the ISM of Elliptical and Spiral Galaxies
- Vortical Motions Driven by Supernova Explosions
- The Intermittent Dissipation of Turbulence: is it Observed in the Interstellar Medium?
- Chemistry in Turbulent Flows
- Supersonic Turbulence in Giant Extragalactic HII Regions
- Turbulence in HII regions: New results
- Hypersonic Turbulence of H2O Masers
- Water Masers Tracing Alfvenic Turbulence and Magnetic Fields in W51 M and W49 N
- Turbulence in the Ursa Major cirrus cloud
- The Collisions of HVCs with a Magnetized Gaseous Disk
- The Initial Stellar Mass Function as a Statistical Sample of Turbulent Cloud Structure
- The Structure of Molecular Clouds: are they Fractal?
- Diagnosing Properties of Turbulent Flows from Spectral Line Observations of the Molecular Interstellar Medium
- Centroid Velocity Increments as a Probe of the Turbulent Velocity Field in Interstellar Molecular Clouds
- High-Resolution C18O Mapping Observations of Heiles' Cloud 2 – Statistical Properties of the Line Width –
- Observations of Magnetic Fields in Dense Interstellar Clouds: Implications for MHD Turbulence and Cloud Evolution
- The Density PDFs of Supersonic Random Flows
- Turbulence as an Organizing Agent in the ISM
- Turbulence and Magnetic Reconnection in the Interstellar Medium
- The Evolution of Self-Gravitating, Magnetized, Turbulent Clouds: Numerical Experiments
- Super–Alfvénic Turbulent Fragmentation in Molecular Clouds
- Decay Timescales of MHD Turbulence in Molecular Clouds
- Numerical Magnetohydrodynamic Studies of Turbulence and Star Formation
- Direct Numerical Simulations of Compressible Magnetohydrodynamical Turbulence
- Fragmentation in Molecular Clouds: The Formation of a Stellar Cluster
- Accretion Disk Turbulence
- List of participants
Summary
We discuss HD and MHD compressible turbulence as a cloud-forming and cloud-structuring mechanism in the ISM. Results from a numerical model of the turbulent ISM at large scales suggest that the phase-like appearance of the medium, the typical values of the densities and magnetic field strengths in the intercloud medium, as well as the velocity dispersion-size scaling relation in clouds may be understood as consequences of the interstellar turbulence. However, the density-size relation appears to only hold for the densest clouds, suggesting that low-column density clouds, which are hardest to observe, are turbulent transients. We then explore some properties of highly compressible polytropic turbulence, in one and several dimensions, applicable to molecular cloud scales. At low values of the polytropic index γ, turbulence may induce the gravitational collapse of otherwise linearly stable clouds, except if they are magnetically subcritical. The nature of the density fluctuations in the high Mach-number limit depends on γ. In the isothermal (γ = 1) case, the dispersion of In (ρ) scales like the turbulent Mach number. The latter case is singular with a lognormal density pdf, while power-law tails develop at high (resp. low) densities for γ < 1 (resp. γ > 1). As a consequence, density fluctuations originating from Burgers turbulence are similar to those of the polytropic case only at high density when γ « 1 and M » 1.
Introduction
One of the main features of turbulence is its multi-scale nature (e.g., Scalo 1987; Lesieur 1990).
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- Interstellar Turbulence , pp. 223 - 231Publisher: Cambridge University PressPrint publication year: 1999
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