SWAS Mapping of Photon Dominated Regions

Details SWAS Mapping of Photon Dominated Regions SWAS Mapping of Photon Dominated Regions

Dec 1999

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999aas...195.6305p&link_type=abstract

American Astronomical Society, 195th AAS Meeting, #63.05; Bulletin of the American Astronomical Society, Vol. 31, p.1465

Astronomy and Astrophysics

Astronomy

1

Scientific paper

One of SWAS's mission goals is to map the emission from the 3P1->3P0 fine-structure transition of neutral carbon ([C I]; ν = 492 GHz) and 13CO J=5->4 (551 GHz) over large scales (> 1o) in molecular clouds. Owing to its low critical density (ncrit 1000 cm-3) and the fact that it arises from a state that is only 24 K above ground, the [C I] line is easily observable throughout the dense interstellar medium. In contrast, 13CO J=5->4 has a relatively high critical density (ncrit 105 cm-3) and the J = 5 level lies at 79 K. We report here on the results of two large-scale mapping projects in Orion A and M17sw. In both sources, we find that the large-scale distribution of [C I] emission is very extended and is very similar to that seen in low J transitions of 13CO. In Orion A the 13CO J=5->4 emission, is undetectable south of the BN/KL object. An LVG analysis of the data shows that the difference between the distribution of [C I] and 13CO J=5->4 emission is most likely the result of temperature and density effects. In M17sw the 13CO J=5->4 emission is more confined to the cloud core than is the [C I], but still extends over most of the cloud. Comparing the intensity ratios of the [C I] and 13CO J=5->4 emission over the entire cloud to PDR models indicates a density range for the emitting gas of a few 104 to 105 cm-3. Even though the excitation requirements for the two transitions are quite different, there is a linear correlation between the intensity of the [C I] and 13CO J=5->4 emission. In a clumpy or filamentary cloud, this could indicate that the distribution of clump densities, temperatures, and sizes is roughly the same over the region, and the line intensities depend on the number of clumps in the SWAS beam. The SWAS team gratefully acknowledges NASA contract NAS5-30702.

Affiliated with

Also associated with

No associations

Rating

SWAS Mapping of Photon Dominated Regions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with SWAS Mapping of Photon Dominated Regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and SWAS Mapping of Photon Dominated Regions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1742540