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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-9248
DTSTART:20250529T203000Z
DTEND:20250529T213000Z
DTSTAMP:20260413T151544Z
LAST-MODIFIED:20250521T122222Z
LOCATION:4421 Sterling Hall
SUMMARY:Small-Scale Structure of the "Dark ISM"\, Astronomy Colloquium
 \, Joanne Dawson\, Macquarie University
DESCRIPTION:It is now known that a significant fraction of the Milky W
 ay ISM resides in a so-called "dark" phase\, usually defined as a mixt
 ure of cold\, optically thick HI and diffuse molecular hydrogen with d
 ensities that are insufficient to form and shield CO. I will present a
  brief overview of the so-called "Dark ISM" -- where it resides\, how 
 much there is\, and its characteristic properties. I will then focus o
 n two aspects of structure in the dark gas: (1) AU-scale structures in
  the cold atomic medium\, including their possible implications in mea
 suring the fraction of cold/opaque HI\, and (2) underlying structure i
 n CO-dark molecular gas that can give rise to very broad\, very weak m
 olecular spectral features in OH and HCO+. I will introduce two ongoin
 g observational experiments that may further constrain both of these p
 henomena.
URL:https://www.physics.wisc.edu/events/?id=9248
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