2001A&A...375L..23T


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST21:55:07

2001A&A...375L..23T - Astronomy and Astrophysics, volume 375, L23-26 (2001/8-4)

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. and WRIGHT G.A.

Abstract (from CDS):

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. (1998ApJ...494L.107K).

Abstract Copyright:

Journal keyword(s): ISM: abundances - atoms - clouds - H II regions - submillimeter

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2001 1
2 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 716 0
3 GAL 332.80-00.60 HII 16 19 47 -51 04.1           ~ 92 1
4 GAL 333.0-00.4 HII 16 20 38.2 -50 40 21           ~ 20 0
5 NGC 6334A HII 17 20 19.3 -35 54 55           ~ 113 0
6 IRAS 17258-3637 HII 17 29 16.7 -36 40 13           ~ 52 0
7 SNR G012.8-00.2 SFR 18 14 14.0 -17 55 50           ~ 218 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-21:55:07

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