AAS Meeting #193 - Austin, Texas, January 1999
Session 118. Star Formation
Oral, Saturday, January 9, 1999, 2:00-3:30pm, Room 6 (A and B)

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[118.03D] The gas dynamics of stellar cluster formation.

C. D. Matzner, C. F. McKee (U.C. Berkeley)

Star formation is typically a collective rather than an individual process, in which the energetic feedback from forming stars regulates further star formation in the same reservoir of self-gravitating gas. This regulation must play a role in the creation of stellar aggregates, from small unbound associations, to massive bound clusters like the Orion Nebula Cluster, to the super star clusters observed in starburst galaxies.

In order to understand the properties of star clusters, we address the gas dynamics of the molecular clumps from which they are born. We apply a virial approach to the motions of magnetized gas in such a clump, invoke the theory of photoionization regulated star formation, and address in detail the the dynamical impact of protostellar outflows on the molecular clump in which they are embedded. Following the clump's evolution during its period of intense star formation, we predict the mass, gravitational binding and radius (if bound) of the star cluster that emerges.

This approach reveals the existence of distinct physical regimes in the behavior of a star-forming, molecular clump. This result may naturally explain the observed differences between low and high-mass cluster-forming regions: the failure of scaling laws to describe high-mass clumps, the very high velocity dispersion and surface density in massive clusters, and the predilection of massive clusters to be bound and of low-mass clusters to be unbound.

The author(s) of this abstract have provided an email address for comments about the abstract: matzner@astron.berkeley.edu

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