The Production of Magnetically Dominated Star Forming Regions

Abstract

We consider the dynamical evolution of an interstellar cloud that is initially in thermal equilibrium in the warm phase and is then subjected to a sudden increase in the pressure of its surroundings. We find that if the initial plasma beta of the cloud is of order unity, then there is a considerable period during which the material in the cloud both has a small beta and is in the thermally unstable temperature range. These conditions are not only consistent with observations of star forming regions, but are also ideally suited to the production of density inhomogeneities by magnetohydrodynamic waves. The end result should be a cloud whose size and average density are typical of Giant Molecular Clouds (GMCs) and which contains denser regions whose densities are in the range inferred for the translucent clumps in GMCs.

arXiv comment9 pages, 3 figures, accepted for publication in ApJ Letters

References in corpus (12)

• The Stellar IMF from Turbulent Fragmentation
• An Origin of Supersonic Motions in Interstellar Clouds
• Turbulent Flow-Driven Molecular Cloud Formation: A Solution to the Post-T Tauri Problem?
• Molecular Cloud Formation in Shock-Compressed Layers
• Global Dynamical Evolution of the ISM in Star Forming Galaxies - I. High Resolution 3D HD and MHD Simulations: Effect of the Magnetic Field
• Physical vs. Observational Properties of Clouds in Turbulent Molecular Cloud Models
• Volume Filling Factors of the ISM Phases in Star Forming Galaxies - I. The Role of the Disk-Halo Interaction
• Comments on Inferences of Star Formation Histories and Birthlines
• The Distribution of Pressures in a Supernova-Driven Interstellar Medium. I. Magnetized Medium
• Analysis of Clumps in Molecular Cloud Models: Mass Spectrum, Shapes, Alignment and Rotation
• The Field Condition: A New Constraint of Spatial Resolution in Simulations of the nonlinear Development of Thermal Instability
• The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations

Cited by in corpus (7)

• The star-forming content of the W3 giant molecular cloud
• Shock-triggered formation of magnetically-dominated clouds
• MHD simulation of the formation of clumps and filaments in quiescent diffuse medium by thermal instability
• The Responses of Magnetically Sub-Critical Cores to Shocks
• The Role of Ambipolar Diffusion in the Formation Process of Moderately Magnetized Diffuse Clouds
• Sheets, filaments and clumps - high resolution simulations of how the thermal instability can form molecular clouds
• Dense core compression and fragmentation induced by the scattering of hydromagnetic waves