Past Events | Department of Astronomy and Astrophysics

2021

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.

Jan 13

Tuesday Lunch Seminar: Yiming Zhong (UChicago) and Mike Zevin (UChicago)

12:00–1:00 pm Zoom

Yiming Zhong will tell us how to seed the first supermassive black holes from
self-interacting dark matter.

Mike Zevin will discuss our current understanding of the various
evolutionary pathways for forming binary black holes, and how
gravitational-wave observations have begun to constrain the relative
efficiencies of these channels as well uncertain physical processes
inherent to massive-star evolution.

Jan 12

Particle Physics Seminar: David Cinabro (Wayne State University/DOE)

3:30–4:30 pm Zoom Room

David Cinabro, Wayne State University/DOE, “Status of Belle II”

Jan 11

2020

Autumn Quarter Ends

All day

Dec 12

Open group seminar: Minghao Guo (Peking University)

4:00–5:00 pm Zoom Room

Minghao Guo, Peking University, “Hunting for Wandering Massive Black Holes”

Dec 11

Postdoc jamboree

2:00–4:00 pm Zoom Room

Join us for the traditional “Postdoc Jamboree” on 12/09 from 2:30pm-4:30pm and 12/11 from 2pm-4pm.
This will be a perfect opportunity to get to know our amazing group of postdocs, a bit about their science and hobbies.

Dec 11

Open Group Seminar: Nandita Khetan (Gran Sasso Science Institute)

1:30–2:30 pm Zoom room

Nandita Khetan, Gran Sasso Science Institute, “A new measurement of the Hubble constant using Type Ia supernovae calibrated with surface brightness fluctuations”

Dec 10