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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:7
UID:UW-Physics-Event-9581
DTSTART:20260430T203000Z
DTEND:20260430T213000Z
DTSTAMP:20260513T145032Z
LAST-MODIFIED:20260414T105948Z
LOCATION:4421 Sterling Hall
SUMMARY:Whitford Lecture: Dust and Molecular Hydrogen in a galaxy with
  3% Solar abundances\, Astronomy Colloquium\, Prof. Bruce Draine\, Pri
 nceton University
DESCRIPTION:The first galaxies form stars out of initially pristine ga
 s.  After a
\nfew million years the gas is enriched with heavy element
 s formed by
\nthe first generation of stars.  Dust starts to appear in
  small
\namounts\, and H2 formation by catalysis on dust grains begins
 .
\n
\nJWST Spectroscopy of I Zw 18\, a very metal-poor star-forming g
 alaxy in
\nthe nearby universe\, provides an opportunity to study thes
 e
\nbeginnings.  The composition of the first dust is found to be very
 
\ndifferent from dust in a mature galaxy such as the Milky Way.  The

 \nmolecular hydrogen emission spectrum allows the ortho/para ratio to 
 be
\ndetermined\, with the ortho/para ratio found to exceed 3 in some 
 regions.
\nImplications will be discussed.
URL:https://www.physics.wisc.edu/events/?id=9581
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