The role of magnetic braking and ambipolar diffusion in the formation of interstellar cloud cores and protostars

The means by which parent molecular clouds give birth to stars constitutes a fundamental unsolved problem in astrophysics. Magnetic fields, which dominate thermal-pressure as a source of support against self-gravity in interstellar molecular clouds, are an important regulator of star-formation. We study the formation and contraction of fragments (or cores) in isothermal, rotating, magnetic molecular clouds. Initial states are exact equilibria with magnetic, centrifugal, and thermal-pressure forces balancing self-gravity. The full nonlinear two-fluid MHD equations for a flattened disk are solved numerically to obtain the cloud's evolution. The evolution of the model clouds is initiated entirely by the onset of magnetic braking (the transport of angular momentum by torsional Alfven waves) and ambipolar diffusion (the relative drift between neutral and charged particles). A core forms and ultimately evolves much more rapidly than the surrounding cloud. A core-envelope separation is demonstrated, and the final mass and angular momentum of the core is determined. Predictions are made for the spatial profiles of important physical quantities, e.g., angular velocity, density, magnetic field. A full parameter study is conducted.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Basu, Shantanu

Contributors dc:contributor

• Mouschovias, T. Ch.

• Physics, General
• Physics, Astronomy and Astrophysics

Statement dc:rights

• Copyright 1993 Basu, Shantanu

Language dc:language

eng

Identifier

AAI9411564
(UMI)AAI9411564

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/20927