Astronomy and Astrophysics – Astrophysics
Scientific paper
Apr 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994a%26a...284..545k&link_type=abstract
Astronomy and Astrophysics (ISSN 0004-6361), vol. 284, no. 2, p. 545-558
Astronomy and Astrophysics
Astrophysics
66
Abundance, Carbon Isotopes, Carbon Monoxide, Emission Spectra, Interstellar Matter, Line Spectra, Photons, Rotational Spectra, Brightness Distribution, Molecular Clouds, Radiative Transfer, Ultraviolet Radiation
Scientific paper
We present a theoretical study of (12)CO and (13)CO rotational line emission from photon dominated regions (PDRs). We incorporate the effects of clumpy cloud structure by computing the physical structures of plane-parallel photo dominated PDRs with finite thickness which are illuminated by UV-radiation fields from either one or both sides. We examine the influence of the gas density (no (H) = 10 4/cu cm to 107/cu cm), the UV intensity (chi = 103 to 106 times the intensity of the average interstellar UV field), the cloud thickness (measured in units of the visual extinction (AV, 2 less than or = AV less than or = 10) and the Doppler width (1 km/s and 3 km/s) on the emergent CO line center brightness temperatures. We explicitly include the effects of the C-13 chemistry on the line intensities. The high brightness temperatures of the (13)CO J = 6 to 5 line observed in several sources can be explained as originating in high density PDRs (n(H) greater than or = 106/cu cm) which are illuminated from two sides and under the assumption that several PDR clumps lie along the line of sight. To model the observed low-J (12)CO and (13)CO line ratios the models require densities of close to 105/cu cm or higher. Due to chemical fractionation the isotopic line intensity ratios for (12)CI/(13)CI can be a factor 2 to 3 lower than the intrinsic isotopic C-12/C-13 ratio. The high-J (12)CO brightness temperatures that we find are in general agreement with earlier PDR models.
Koester Ben
Sternberg Amiel
Stoerzer Herbert
Stutzki Juergen
No associations
LandOfFree
Carbon monoxide line emission from 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 Carbon monoxide line emission from photon dominated regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Carbon monoxide line emission from photon dominated regions will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1254221