A&A Colloquium: Eve Ostriker (Princeton)

3:30–4:30 pm Zoom - for link, please contact, Laticia

"Star Formation and "feedback" in Giant Molecular Clouds"

Giant molecular clouds (GMCs) are the home of the most extreme conditions and the most dramatic events found in the interstellar medium (ISM). GMCs host the densest, coldest portion of the ISM’s gas, with gravitational collapse occurring in filaments and leading to the formation of star clusters.  These young star clusters, in turn, host massive and luminous stars that profoundly alter — and ultimately destroy — their birth clouds, by an array of feedback processes.  Historically, the effect of these ``feedback’’ processes was seen as optical emission nebulae centuries before — in the 1600s! —  direct observations of molecular gas that makes up the majority of a cloud’s mass.  In addition to the UV radiation that ionizes gas and creates highly-photogenic nebulae, non-ionizing UV also is important in applying radiation forces to dust.  Stellar winds from massive stars are also present, but X-ray evidence of their impact its less apparent than expected, a longstanding puzzle.  These feedback processes all contribute in shaping the evolution of GMCs, and it is believed that star formation is finally truncated by feedback-induced dispersal of gas, thereby setting the lifetime star formation efficiency.  Within GMCs, turbulence plays several important and counteracting roles, including reducing star formation rates by dispersing dense regions, increasing porosity so that destructive radiation escapes, and mixing hot and cool gas at the fractal interface surrounding hot wind bubbles.
Given the complex array of processes involved, numerical simulations are essential to developing quantitative models of the lives and deaths of star-forming GMCs, and provide a laboratory for us to investigate the detailed physics of feedback.  In this talk, I will describe results from recent radiation (magneto-) hydrodynamic simulations and theoretical models that have helped us to understand how star-forming GMCs self-regulate and guide the evolution of galaxies.

Event Type

Colloquia, Seminars, Talks

Jan 13