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 in the Ursa Major cirrus cloud
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
High resolution 21 cm observations of the Ursa Major cirrus revealed highly filamentary structures down to the 0.03 pc resolution. These filaments, still present in the line centroid map, show multi-Gaussian components and seem to be associated with high vorticity regions. Probability density functions of line centroid increments and structure functions were computed on the line centroid field, providing strong evidences for the presence of turbulence in the atomic gas.
Introduction
Many statistical studies of the density and velocity structure of dense interstellar matter have been done on molecular clouds where turbulence is seen as a significant support against gravitational collapse that leads to star formation. Less attention has been devoted to turbulence in the Galactic atomic gas (HI). The cold atomic component (T ∼ 100 K, n ∼ 100 cm−3), alike molecular gas, is characterized by multiscale self-similar structures and non-thermal linewidths.
A detailed and quantitative study of the turbulence and kinematics of HI clouds has never been done. Here we present a preliminary analysis of this kind based on high resolution 21 cm observations of an HI cloud located in the Ursa Major constellation. To characterize the turbulent state of the atomic gas, a statistical analysis of the line centroid field has been done. We have computed probability density functions of line centroid increments and structure functions.
HI Observations
The Ursa Major cirrus (α(2000) = 9h36m, δ(2000) = 70°20′) has been observed with the Penticton interferometer.
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- Interstellar Turbulence , pp. 169 - 173Publisher: Cambridge University PressPrint publication year: 1999
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