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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20120626T123000
DTEND;TZID=Atlantic/Canary:20120626T133000
UID:iactalks-397
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/397
CREATED:2012-06-26T12:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:The 1D plane-parallel PDR model and its application
DESCRIPTION:The 1D plane-parallel PDR model and its application\nDr. Jonath
 an Heiner\n\nA simple model using the balance of photodissociation assumin
 g a  one-dimensional plane-parallel model yields total hydrogen volume  de
 nsities for a column of atomic hydrogen under the influence of a  far-ultr
 aviolet radiation field. This can be applied wherever atomic  hydrogen can
  be assumed to be the product of photodissociation, or  perhaps where it i
 s being kept in its atomic state because of the local  radiation field. I 
 have previously applied this model to the nearby spiral galaxies M33,  M81
  and M83 in the past, but the application is mostly manual and  cumbersome
 . In order to make this method suitable to apply to larger  samples of gal
 axies, we developed an automated procedure that identifies  candidate PDRs
 , calculates the balance of photodissociation at  locations where PDR-prod
 uced HI can be expected and provides total  hydrogen volume densities. We 
 applied the procedure to M83 as a  consistency check. It is also ready to 
 take advantage of the latest  integral field spectroscopy data (metallicit
 y), which we did in the case  of M74. In principle this procedure is most 
 suitable to probe the diffuse  interstellar medium at the edges of HII reg
 ions in other galaxies than  our own. However, if detailed morphological i
 nformation is already  available, we can improve our understanding of the 
 method by applying it  to very specific cases, such as parts of the Taurus
  molecular cloud.  While the results are highly sensitive to the local mor
 phology, they can  potentially be used as an independent probe of the mole
 cular gas.
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