Cornell University, Department of Physics Colloquium - Salpeter Lecture
Abstract: Stars form in the darkest regions of our Galaxy. Barnard’s deep, wide-field, photographs revealed web-like structures within these regions 100 years ago. But, somehow, it took a century--until roughly now-- for us to realize that the detailed structure of Barnard’s “dark webs” might hold astrophysical secrets. Over the past few decades, ever-higher-resolution multi-wavelength observations and simulations of interstellar gas and dust have all revealed more and more intricate networks and twists of filaments on scales from hundreths to hundreds of parsecs. We are relatively certain that the interplay of gravity, stellar feedback, and magnetic fields creates the features of the dark web we see, but we are not sure how long it takes to create the various structures, how long they last, or how (much) matter flows along them. On the largest scales, I will discuss the extraordinarily long and thin “Bones” of the Galaxy, and on the smallest scales, I will zoom in on stellar nurseries where new interferomeric observations and new MHD simulations combine to suggest that stars may form through very asymmetric, and potentially sporadic, accretion processes, rather than through the slow gravitational collapse of an isolated blob of gas.