Abstract: Recent observational and numerical evidence suggests that star-forming molecular clouds may be in a process of global, hierarchical gravitational contraction, rather than supported against their self-gravity by magnetic fields or turbulence. I will briefly review the evidence favoring this view and then its mechanism and main implications: the sequential onset of collapse at different mass scales, constituting a hierarchy of collapses within collapses; the formation of filamentary structures by anisotropy amplification and their role in feeding star-forming clumps; and the acceleration of star formation until a feedback burst quickly and abruptly terminates it. The star clusters formed in this environment exhibit primordial age and mass segregation, an age distribution peaked at the time of the burst with a tail of older objects, and a hierarchy of subgroups that begin to mix when gas is expelled by the burst.
Astro Colloquium and 'coffee & cookies' Department gathering (3:45-4:00pm)
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