EPoS Contribution
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Dynamical Structure of Molecular Cloud Cores
Enrique Vazquez-Semadeni Centro de Radioastronomia y Astrofisica-UNAM, Morelia, Mexico |
We discuss the meaning of Bonnor-Ebert (BE) density profiles in molecular cloud cores. Noting that their normalized functional form is indistinguishable from that of dynamically collapsing solutions, we argue that no claim of hydrostatic equilibrium can be made on the basis of the presence of a BE density profile alone. This holds even if the profile corresponds to a stable configuration, because a warm confining medium, which allows for a stable equilibrium, is not necessarily available within their parent molecular clouds. Therefore, we suggest that the true test of equilibrium is provided by the velocity field, not the density profile, and that a BE profile is just indicative of a regime in which the main agent opposing self-gravity is the thermal pressure. We furthermore investigate numerically the stage at which a BE density profile appears for objects whose collapse is triggered by external compressions applied to initially uniform, isothermal gas parcels within a molecular cloud. |