The formation of globular clusters

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6139528

Murray, S D

The formation of globular clusters is studied, beginning with star formation. It is proposed that the fragmentation of a protocluster proceeded in two steps. First, perturbations grew rapidly due to thermal instability. The perturbations then had short timescales for the growth of gravitational instabilities, so that fragmentation could be completed on a timescale much less than the dynamical timescale of the parent cloud. The process is modeled using one-dimensional hydrodynamic simulations of clouds both with and without external heat sources. The models include the effects of a nonequilibrium H2 abundance. Cloud-cloud collisions are also simulated. Gravitational instability is investigated by numerically integrating the evolution of Lagrangian perturbations of the fluid variables. Protoclusters form in a protogalactic cloud cooling from its virial temperature. Dynamical effects on the growth of perturbations in these clouds are examined. Finally, collisional mechanisms are examined by which metals can diffuse throughout a protocluster before star formation can occur. It is found that collisional diffusion is too slow for metals to diffuse throughout an entire protocluster on acceptable time scales. Metals may, however, be able to diffuse throughout the star forming regions in cloud-cloud collisions. If the iron and CNO elements are preferentially contained in grains of different sizes, then this latter process might explain the existence of uniformities in (Fe/H) coincidentally in clusters which show CNO variations.

• Research Organization: California Univ., Santa Cruz, CA (USA)
• OSTI ID: 6139528
• 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
COLLISIONS
COMPUTERIZED SIMULATION
COOLING
DATA
DIFFUSION
DISTURBANCES
ELEMENTS
FLUID MECHANICS
FRAGMENTATION
HEAT SOURCES
HYDRODYNAMICS
HYDROGEN
INFORMATION
INSTABILITY
MECHANICS
METALS
NONMETALS
NUMERICAL DATA
SIMULATION
STAR CLUSTERS
STAR EVOLUTION
THEORETICAL DATA