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The molecular component of the Galaxy is comprised of turbulent, magnetized clouds, many of which are self-gravitating and form stars. To develop an understanding of how these clouds' kinetic and structural evolution may depend on their level of turbulence, mean magnetization, and degree of self-gravity, we perform a survey of direct numerical MHD(More)
We review current understanding of star formation, outlining an overall theoretical framework and the observations that motivate it. A conception of star formation has emerged in which turbulence plays a dual role, both creating overdensities to initiate gravitational contraction or collapse, and countering the effects of gravity in these overdense regions.(More)
The under-abundance of very massive galaxies in the Universe is frequently attributed to the effect of galactic winds. Although ionized galactic winds are readily observable, most of the expelled mass (that is, the total mass flowing out from the nuclear region) is likely to be in atomic and molecular phases that are cooler than the ionized phases.(More)
Velocity anisotropy induced by MHD turbulence is investigated using computational simulations and molecular line observations of the Taurus molecular cloud. A new analysis method is presented to evaluate the degree and angle of velocity anisotropy using spectroscopic imaging data of interstellar clouds. The efficacy of this method is demonstrated on model(More)
Using one-dimensional hydrodynamic simulations including interstellar heating , cooling, and thermal conduction, we investigate nonlinear evolution of gas flow across galactic spiral arms. We model the gas as a non-self-gravitating, un-magnetized fluid, and follow its interaction with a stellar spiral potential in a local frame comoving with the stellar(More)
We analyze the spectral properties of driven, supersonic compressible magne-tohydrodynamic (MHD) turbulence obtained via high-resolution numerical experiments , for application to understanding the dynamics of giant molecular clouds. Via angle-averaged power spectra, we characterize the transfer of energy from the intermediate, driving scales down to(More)
We present two-dimensional hydrodynamical simulations of both jet-and wind-driven models for protostellar outflows in order to make detailed comparisons to the kinematics of observed molecular outflows. The simulations are performed with the ZEUS-2D hydrodynamical code using a simplified equation of state, simplified cooling and no external heating, and no(More)
This paper reviews current theoretical work on the various stages of accretion in protostars, and the relationship of these ideal stages to the spectral classes of observed protostellar systems. I discuss scaling relationships that have been obtained for models of pre-stellar cores as they evolve by ambipolar diffusion toward a central singularity, and(More)
Using time-dependent linear perturbation theory, we evaluate the dynamical friction force on a massive perturber M p traveling at velocity V through a uniform gaseous medium of density ρ 0 and sound speed c s. This drag force acts in the direction − ˆ V , and arises from the gravitational attraction between the perturber and its wake in the ambient medium.(More)