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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-5075
DTSTART:20190404T203000Z
DTEND:20190404T220000Z
DTSTAMP:20260417T132313Z
LAST-MODIFIED:20190314T192835Z
LOCATION:4421 Sterling Hall\, Coffee and cookies 3:30 PM\, Talk begins
  3:45 PM
SUMMARY:Science with a Complete Catalog of Galactic HII Regions\, Astr
 onomy Colloquium\, Loren Anderson\, West Virginia University
DESCRIPTION:HII regions are the signature of ongoing high-mass star fo
 rmation\, and are key to understanding star formation and feedback. Mo
 dern mid-infrared surveys have for the first time enabled a complete c
 ensus of Galactic HII regions\, and with such a census we can get a gl
 obal view of high-mass star formation in the Milky Way.  We found that
  all HII regions have the same mid-infrared morphology of ~20um emissi
 on surrounded by ~10um emission.  The former is largely due to small g
 rains scholastically heated in the HII region plasma and the latter is
  mostly caused by emission from polycyclic aromatic hydrocarbons.  We 
 used mid-infrared survey data to create a catalog of all objects shari
 ng this morphology in the Galaxy\, the "WISE Catalog of Galactic HII R
 egions."  This catalog has over 8000 entries\, ~2000 of which are know
 n to be HII regions\, ~2000 of which are HII region candidates with ra
 dio continuum emission from ionized gas\, and ~4000 of which are radio
 -quiet candidates. Radio recombination line observations can turn HII 
 region candidates into known regions\, and radio continuum observation
 s can turn radio quiet candidates into candidates.  I will detail our 
 efforts on these two fronts\, which together have allowed us to determ
 ine the Galactic locations of a large number of HII regions and to est
 imate the overall HII region population.<br>
\n<br>
\nOver large porti
 ons of the Milky Way\, the WISE catalog is now statistically complete 
 for all HII regions ionized by single O-stars.  With such a catalog\, 
 we can begin to examine the overall Galactic HII region population\, a
 nd to compare massive star formation in the Milky Way with that of ext
 ernal galaxies.  Our current investigations include the z-distribution
  of massive star formation regions and the Sun's height above the midp
 lane\, the form Galactic HII region luminosity function\, massive star
  formation in the far outer Galaxy\, the Galactic electron temperature
  gradient\, a strange cluster of HII regions near to the Galactic cent
 er\, the distribution of ionized gas in the inner Galaxy\, and the lum
 inosity and star formation rate of the Milky Way.
URL:https://www.physics.wisc.edu/events/?id=5075
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