Density structure and star formation in dense cores with thermal and nonthermal motions

An equilibrium model of a spherically symmetric dense core which incorporates both thermal and nonthermal motions is presented. The thermal motions are spatially uniform, and the nonthermal motions increase with radius r as a power law, as indicated by observations. This 'TNT' model uses the spatial structure of the thermal and nonthermal motions to specify the core density structure in hydrostatic equilibrium. The infall of the TNT core is solved approximately by assuming the outward propagation of an 'expansion wave' at the effective sound speed, which increases with radius in the core. The radial structure of the velocity dispersion, density, and mass included within r are calculated for core parameters taken to represent typical 'massive' cores. The TNT massive core can form a star with 10 solar masses in 1,000,000 yr, more quickly than the corresponding single isothermal sphere core by a factor of 2.