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Spectral imaging of the Orion Bar at 3.3, 8.4, and 11.3 microns: Comparison with a fluorescent polycyclic aromatic hydrocarbon modelSpectral images were obtained of the Orion Bar which sample polycyclic aromatic hydrocarbon (PAH) emission at 3.3, 8.4, and 11.3 micrometers. The images are strikingly different even though they all sample PAH emission. In particular, the 3.3 and 11.3 micrometers images sample PAH emission from C-H bonds, yet the 3.3 micrometers image contains many small bright knots while the 11.3 micrometers image is much more uniform. For comparison with a fluorescent PAH model, a data set was created from the measured intensities of 250 locations in each image. From the comparison, we conclude that: (1) the size distribution of PAHs varies within the Bar, with the bright 3.3 micrometers knots containing the largest proportion of small PAHs; (2) the points along the front of the Bar have emission cross sections characteristic of neutral PAHs while within the Bar, the emission cross sections are different, consistent with the PAHs being charged; (3) the PAHs along the front of the Bar are larger than average for the Bar; (4) emission along the back of the Bar is consistent with PAH emission in an attenuated UV radiation field; (5) there is no evidence for PAH dehydrogenation.
Document ID
19950033879
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bregman, Jesse
(NASA Ames Research Center Moffett Field, CA, United States)
Larson, Kristen
(UCSC, Santa Cruz, CA United States)
Rank, David
(UCSC, Santa Cruz, CA United States)
Temi, Pasquale
(UCSC, Santa Cruz, CA United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1994
Publication Information
Publication: The Astrophysical Journal, Part 1
Volume: 423
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A65478
Distribution Limits
Public
Copyright
Other

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