Star formation in the presence of magnetic fields: Molecular cloud core formation and dynamical contraction due to ambipolar diffusion; a simulation with axial symmetry

Interstellar molecular clouds are generally believed to be the sites of active star formation in our galaxy. Observed densities, temperatures, and magnetic field strengths imply that well-ordered magnetic fields dominate thermal pressure in supporting these objects against self-gravity. The magnetic force is transferred to the neutrals through collisions with ions. Because the degree of ionization drops as the density increases, redistribution of the mass-to-flux ratio in a cloud's central flux tubes (ambipolar diffusion) takes place at an ever-increasing rate, leading to the formation of high-density cores, typically after 8 million years of quasi-static contraction. Eventually, the central mass-to-flux ratio exceeds the critical value for collapse, and the core begins to contract rapidly.

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

• Fiedler, Robert Anthony

• Physics, Astronomy and Astrophysics

Statement dc:rights

• Copyright 1990 Fiedler, Robert Anthony

Language dc:language

eng

Identifier

AAI9114234
(UMI)AAI9114234

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/20550