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

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5156812

Fiedler, R A

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 the 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. The full nonlinear, non-ideal magnetohydrodynamic equations are solved by using a new, nonorthogonal, fully adaptive grid describing the evolution of a set of non-rotating, axially symmetric model clouds.

• Research Organization: Illinois Univ., Urbana, IL (United States)
• OSTI ID: 5156812
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
COSMIC DUST
DATA
DUSTS
FLUID FLOW
FLUID MECHANICS
GALACTIC EVOLUTION
GRAVITATIONAL COLLAPSE
HYDRODYNAMICS
INFORMATION
INTERACTIONS
MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETOHYDRODYNAMICS
MATHEMATICAL MODELS
MECHANICS
NUMERICAL DATA
PARTICLE INTERACTIONS
STAR EVOLUTION
STAR MODELS
STELLAR ATMOSPHERES
THEORETICAL DATA