NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
PAHs as Probes of Photodissociation Regions in M17 and the Orion BarWe have obtained narrow-band images of M17 SW and the Orion Bar in the PAH emission bands and pedestal (3.29, 3. 36, 3. 42 microns) The emission bands at 3.3 and 3.4 microns arise from the photodissociation regions (PDRs) between ionized gas and molecular clouds. In both M17 SW and the Orion Bar, the PDRs are nearly edge-on, providing excellent opportunities for comparing models of PDRs with observations. We observe an exponential drop in the strength of the 3.3 micron emission with a 1/e distance of 9 arcsec in Orion and 5 arcsec in M17 SW, in good agreement with previous observations. These results show that the two regions are very similar, and they imply that the mean density is 2.4 times higher in the Orion Bar than in the M17 SW PDR. However, we also find that in the Orion Bar, the ratio of the 3.4 micron emission to the 3.3 micron emission is consistent with the 1/e distance of 3 arcsec determined from PDR models fit to the molecular H and CO in the Orion Bar. We are presently investigating how the main band can imply that the UV field is dropping with a 1/e distance of 9 arcsec while the model PDR predicts a 1/e distance of 3 arcsec.
Document ID
20020038725
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Sloan, G. C.
(NASA Ames Research Center Moffett Field, CA United States)
Bregman, J. D.
(NASA Ames Research Center Moffett Field, CA United States)
Schultz, A.
(NASA Ames Research Center Moffett Field, CA United States)
Temi, P.
(California Univ. Santa Cruz, CA United States)
Rank, D. M.
(California Univ. Santa Cruz, CA United States)
Witteborn, Fred C.
Date Acquired
August 20, 2013
Publication Date
January 1, 1995
Subject Category
Astronomy
Meeting Information
Meeting: ESO Workshop on the Role of Dust in the Formation of Stars
Location: Munich
Country: Germany
Start Date: September 11, 1995
End Date: September 14, 1995
Funding Number(s)
PROJECT: RTOP 352-02-03
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available