Tufts/CfA/MIT Cosmology Seminar, at the CfA:

Tuesday, December 5, 2000
12:30 pm
Harvard-Smithsonian Center for Astrophysics
Pratt Conference Room (G04)

"Theoretical Modelling of Ultra-Compact HII Regions and the Formation of Super Star Clusters"


Jonathan Tan
University of California at Berkeley

Abstract:

Ultracompact (UC) HII regions herald the earliest stage of high mass stellar feedback on the interstellar medium. Understanding this process is a crucial element for theories of massive star formation. We present a semi-analytic model of pre-supernova feedback on a clumpy, turbulent and self-gravitating gas cloud that combines ionization, stellar winds and radiation pressure. One of the biggest puzzles of UC HII regions is their observed longevity, since it appears that thermal pressure is insufficient to confine the ionized gas. We find the turbulent motion of neutral gas enhances mass loading of the HII region, sufficient to solve this "lifetime" problem. Extrapolating Galactic massive star forming regions to much greater masses and assuming constant SFRs before the cloud is destroyed, we find that high (~50%) star formation efficiencies are possible, allowing for the creation of gravitationally bound "super" star clusters.

Return to Joint Cosmology Seminar home page.