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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2135
DTSTART:20110310T213000Z
DURATION:PT1H0M0S
DTSTAMP:20260420T134558Z
LAST-MODIFIED:20110303T140901Z
LOCATION:4421 Sterling Hall
SUMMARY:The Formation of Molecular Clouds and Massive Stars\, Astronom
 y Colloquium\, Mordecai-Mark Mac Low\, American Museum of Natural Hist
 ory
DESCRIPTION:In this talk I consider two questions.  First\, I investig
 ate the formation of molecular clouds from diffuse interstellar gas.  
 It has been argued that the midplane pressure controls the fraction of
  molecular hydrogen present\, and thus the star formation rate. Altern
 atively\, I and others have suggested that the gravitational instabili
 ty of the disk controls both.  I present numerical results demonstrati
 ng that the observed correlations between midplane pressure\, molecula
 r hydrogen fraction\, and star formation rate can be explained within 
 the gravitational instability picture.  Second\, I discuss how ionizat
 ion affects the formation of massive stars. Although most distinctive 
 observables of massive stars can be traced back to their ionizing radi
 ation\, it does not appear to have a strong effect on their actual for
 mation.  Rather\, I present simulations suggesting that stars only ion
 ize large volumes after their accretion has already been throttled by 
 gravitational fragmentation in the accretion flow. At the same time th
 ese models can explain many aspects of the observations of ultracompac
 t H II regions.&lt\;br&gt\;<br><br>
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URL:https://www.physics.wisc.edu/events/?id=2135
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