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SEQUENCE:1
UID:UW-Physics-Event-4776
DTSTART:20180308T093000Z
DTEND:20180308T230000Z
DTSTAMP:20260419T035128Z
LAST-MODIFIED:20180305T162655Z
LOCATION:4421 Sterling Hall\, 3:30 PM Coffee and cookies\, 3:45 PM Tal
 k Begins
SUMMARY:Probing Composition and Alignment of Interstellar Dust Grains 
 via Stratospheric Observations of Dust Emission Polarization Spectra \
 , Astronomy Colloquium\, Giles Novak\, Northwestern University and CIE
 RA
DESCRIPTION:Astronomers have known about interstellar dust particles f
 or almost a century\, and for most of this time we have also known tha
 t these spinning grains somehow become aligned with respect to the amb
 ient interstellar magnetic field.  However\, our knowledge of the grai
 ns’ composition is very incomplete\, as is our understanding of the 
 grain alignment mechanism.  Such information is needed if we are to (a
 ) remove the contaminating dust signal from cosmological observations 
 of gravity waves from the inflationary epoch\, and (b) efficiently exp
 loit polarimetry of aligned grains to study the role of magnetic field
 s in star/planet formation.  By describing two recent observations\, I
  will show how measurements of the polarization spectrum of dust emiss
 ion can help fill in the gaps in our knowledge of grain composition an
 d alignment.  These two observations are (1) the first measurement of 
 the submillimeter polarization spectrum of a translucent molecular clo
 ud\, that my collaborators and I obtained with a balloon-borne experim
 ent flown over Antarctica\, and (2) the first observation of a far-IR 
 polarization spectrum that rises with increasing wavelength as predict
 ed by models\, made toward the nearby stellar nursery Rho Oph using th
 e new polarimeter for the Stratospheric Observatory For Infrared Astro
 nomy (SOFIA). 
URL:https://www.physics.wisc.edu/events/?id=4776
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