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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20121204T123000
DTEND;TZID=Atlantic/Canary:20121204T133000
UID:iactalks-454
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/454
CREATED:2012-12-04T12:30:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:How dynamical environment regulates the structure of the molecular 
 gas and star formation in M51 
DESCRIPTION:How dynamical environment regulates the structure of the molecu
 lar gas and star formation in M51 \nDr. Sharon Meidt\n\nGas kinematics on 
 the scales of Giant Molecular  Clouds (GMCs) are essential for probing the
  framework that links the  large-scale organization of interstellar gas to
  cloud formation and  subsequent star formation.  I will present an overvi
 ew of results from the  PdBI Arcsecond Whirlpool Survey (PAWS, PI: E. Schi
 nnerer), which has mapped  CO(1-0) emission over 9 kpc in the nearby grand
 -design spiral galaxy M51 at  40 pc resolution, and is sensitive to giant 
 molecular clouds (GMCs) with  masses above 10^5 Msun.  This unprecedented 
 view challenges the  conventional picture of how molecular gas is structur
 ed and organized in  galaxies: clouds are not ‘universal’, but
  respond to their environment,  resulting in a diversity of cloud properti
 es that not only depend on  (dynamical) environment but also vary from gal
 axy to galaxy.  I will  discuss how this sensitivity to environment emerge
 s, in consideration of  the stability of M51’s GMCs (including the e
 ffects of pressure, shear,  turbulence) and our view of non-circular motio
 ns in the gas disk.  As a  result of the strong streaming motions that ari
 se due to departures from  axisymmetry in the gravitational potential (i.e
 . the nuclear bar and spiral  arms), embedded clouds feel a reduced surfac
 e pressure, which can prevent  collapse.   This dynamical pressure natural
 ly leads to changes in the  efficiency of star formation and hence gas dep
 letion time along the spiral  arms.  I will show that local reductions to 
 cloud surface pressure in M51  dominate over shear and star formation feed
 back-driven turbulence in  determining the observed radial variation the d
 epletion time.  I will also  describe how incorporating a dynamical pressu
 re term to the canonical  free-fall time produces a single star formation 
 law that can be applied to  all star-forming regions and galaxies, across 
 cosmic time.
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