13CI in high-mass star-forming clouds
We report measurements of the 12C/13C abundance ratio in the three galactic regions G 333.0-0.4, NGC 6334 A and G 351.6-1.3 from observations of the 12CI 3P2-3P1 transition and the hyperfine components of the corresponding 13CI transition near 809 GHz. These transitions were observed simultaneously...
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ftcern:oai:cds.cern.ch:499512 2023-05-15T18:22:45+02:00 13CI in high-mass star-forming clouds Tieftrunk, A R Jacobs, K Martin, C L Siebertz, O Stark, A A Stutzki, J Walker, C K Wright, G A 2001 http://cds.cern.ch/record/499512 eng eng http://cds.cern.ch/record/499512 astro-ph/0105176 oai:cds.cern.ch:499512 Astrophysics and Astronomy 2001 ftcern 2018-07-28T05:00:39Z We report measurements of the 12C/13C abundance ratio in the three galactic regions G 333.0-0.4, NGC 6334 A and G 351.6-1.3 from observations of the 12CI 3P2-3P1 transition and the hyperfine components of the corresponding 13CI transition near 809 GHz. These transitions were observed simultaneously with the CO 7-6 line emission at 806 GHz with the AST/RO telescope located at the South Pole. From a simultaneous fit to the 12CI 3P2-3P1 transition and the HF components of the corresponding 13CI transition and an independent estimate of an upper limit to the optical depth of the 12CI emission we determine intrinsic 12CI/13CI column density ratios of 23+-1 for G 333.0-0.4, 56+-14 for NGC 6334 A and 69+-12 for G 351.6-1.3. As the regions observed are photon dominated, we argue that the apparent enhancement in the abundance of 13C towards G 333.0-0.4 may be due to strong isotope-selective photodissociation of 13CO, outweighing the effects of chemical isotopic fractionation as suggested by models of PDRs. Towards NGC 6334 A and G 351.6-1.3 these effects appear to be balanced, similar to the situation for the Orion Bar region observed by Keene et al. (1998). Other/Unknown Material South pole CERN Document Server (CDS) Orion ENVELOPE(-59.800,-59.800,-62.438,-62.438) South Pole |
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CERN Document Server (CDS) |
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ftcern |
language |
English |
topic |
Astrophysics and Astronomy |
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Astrophysics and Astronomy Tieftrunk, A R Jacobs, K Martin, C L Siebertz, O Stark, A A Stutzki, J Walker, C K Wright, G A 13CI in high-mass star-forming clouds |
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Astrophysics and Astronomy |
description |
We report measurements of the 12C/13C abundance ratio in the three galactic regions G 333.0-0.4, NGC 6334 A and G 351.6-1.3 from observations of the 12CI 3P2-3P1 transition and the hyperfine components of the corresponding 13CI transition near 809 GHz. These transitions were observed simultaneously with the CO 7-6 line emission at 806 GHz with the AST/RO telescope located at the South Pole. From a simultaneous fit to the 12CI 3P2-3P1 transition and the HF components of the corresponding 13CI transition and an independent estimate of an upper limit to the optical depth of the 12CI emission we determine intrinsic 12CI/13CI column density ratios of 23+-1 for G 333.0-0.4, 56+-14 for NGC 6334 A and 69+-12 for G 351.6-1.3. As the regions observed are photon dominated, we argue that the apparent enhancement in the abundance of 13C towards G 333.0-0.4 may be due to strong isotope-selective photodissociation of 13CO, outweighing the effects of chemical isotopic fractionation as suggested by models of PDRs. Towards NGC 6334 A and G 351.6-1.3 these effects appear to be balanced, similar to the situation for the Orion Bar region observed by Keene et al. (1998). |
author |
Tieftrunk, A R Jacobs, K Martin, C L Siebertz, O Stark, A A Stutzki, J Walker, C K Wright, G A |
author_facet |
Tieftrunk, A R Jacobs, K Martin, C L Siebertz, O Stark, A A Stutzki, J Walker, C K Wright, G A |
author_sort |
Tieftrunk, A R |
title |
13CI in high-mass star-forming clouds |
title_short |
13CI in high-mass star-forming clouds |
title_full |
13CI in high-mass star-forming clouds |
title_fullStr |
13CI in high-mass star-forming clouds |
title_full_unstemmed |
13CI in high-mass star-forming clouds |
title_sort |
13ci in high-mass star-forming clouds |
publishDate |
2001 |
url |
http://cds.cern.ch/record/499512 |
long_lat |
ENVELOPE(-59.800,-59.800,-62.438,-62.438) |
geographic |
Orion South Pole |
geographic_facet |
Orion South Pole |
genre |
South pole |
genre_facet |
South pole |
op_relation |
http://cds.cern.ch/record/499512 astro-ph/0105176 oai:cds.cern.ch:499512 |
_version_ |
1766202164275838976 |