SIMBAD references

2014A&A...564A..68S - Astronomy and Astrophysics, volume 564A, 68-68 (2014/4-1)

High abundance ratio of 13CO to C18O toward photon-dominated regions in the Orion-A giant molecular cloud.

SHIMAJIRI Y., KITAMURA Y., SAITO M., MOMOSE M., NAKAMURA F., DOBASHI K., SHIMOIKURA T., NISHITANI H., YAMABI A., HARA C., KATAKURA S., TSUKAGOSHI T., TANAKA T. and KAWABE R.

Abstract (from CDS):

We derive physical properties such as the optical depths and the column densities of 13CO and C18O to investigate the relationship between the far ultraviolet (FUV) radiation and the abundance ratios between 13CO and C18O. We have carried out wide-field (0.4deg2) observations with an angular resolution of 25.8'' (∼0.05pc) in 13CO (J=1-0) and C18O (J=1-0) toward the Orion-A giant molecular cloud using the Nobeyama 45m telescope in the on-the-fly mode. Overall distributions and velocity structures of the 13CO and C18O emissions are similar to those of the 12CO (J=1-0) emission. The optical depths of the 13CO and C18O emission lines are estimated to be 0.05<τ(13CO)<1.54 and 0.01<τ(C18O)<0.18, respectively. The column densities of the 13CO and C18O emission lines are estimated to be 0.2x1016<N(13CO)<3.7x1017cm–2 and 0.4x1015<N(C18O)<3.5x1016cm–2, respectively. The abundance ratios between 13CO and C18O, X13CO/XC18^O_, are found to be 5.7-33.0. The mean value of X(13CO)/X(C18O) in the nearly edge-on photon-dominated regions is found to be 16.47±0.10, which is a third larger than that the solar system value of 5.5. The mean value of X(13CO)/X(C18O) in the other regions is found to be 12.29±0.02. The difference of the abundance ratio is most likely due to the selective FUV photodissociation of C18O.

Abstract Copyright:

Journal keyword(s): ISM: abundances - ISM: clouds - photon-dominated region - ISM: individual objects: Orion-A

VizieR on-line data: <Available at CDS (J/A+A/564/A68): list.dat fits/*>

CDS comments: Fig. 1 DLSF, Region D and M43 Shell not in SIMBAD.

Simbad objects: 20

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2019.09.18-01:59:10

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