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Session 20 - Chemistry & Physical Process in the ISM.
Display session, Wednesday, January 07
Exhibit Hall,

[20.03] The Formation of Molecular Cloud Cores

C. Curry, S. W. Stahler (UC Berkeley)

We present preliminary results from a detailed, numerical study of gravitational condensation in an unbounded, magnetized medium. The calculation is intended to model each stage in the formation of a dense core, similar to those found within star-forming regions, out of its parent molecular cloud. We assume that the evolution proceeds quasi-statically, through the combined action of self-gravity and ambipolar diffusion. The condensation is followed from its origin as a small perturbation in an initially homogeneous background medium of density \rho_0, until the point when its central density is \sim 10^2 \rho_0. The evolution is characterized by three distinct epochs: (i) an early growth phase, in which the region of interest grows to a size somewhat larger than the Jeans' length in the background medium; (ii) a pivotal phase, marked by the detachment of the (now self-gravitating) cloud from the background; and (iii) a contracting phase, in which the central density rapidly increases, while the cloud continues to accrete gas from the background. We compare our results from phase (iii) with the properties inferred from molecular line studies.

Program listing for Wednesday