Astronomy Colloquium - Eve Ostriker
Thursday, January 25, 2018 - 2:30pm
- Eve Ostriker
"Star Formation and feedback: from clouds to the cosmos"
For many decades, the regulation of star formation was considered one of the most vexing unsolved problems in astrophysics, but with a combination of sophisticated numerical hydrodrodynamic models and idealized theoretical analyses, we have made remarkable recent progress. Central to this progress has been development of the concept of self-regulation, which relies on quantitative evaluation of the effects of energetic “feedback” from star formation. This feedback dominates the dynamics and thermodynamics of the interstellar medium (ISM), the reservoir of future star formation. Energy returnedn by young, massive stars to their surroundings determines the state of the ISM, which in turn determines the rate and character of star formation. Different forms of feedback are important at different scales, from individual cluster-forming molecular clouds, to the three-phase ISM in galactic disks, to galaxy evolution over cosmic time. In my talk, I will discuss the governing physical processes and present results from numerical MHD and RHD simulations. With these simulations, we are able to follow the radiation feedback that photoionizes and disperses individual star-forming clouds, and the supernova feedback that creates the hot ISM, maintains turbulence in the cold ISM, and drives large-scale galactic winds and fountains. While many questions remain unanswered, the importance of quantifying all the forms of star formation feedback is now more clear than ever.
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