Publication Abstracts

Cohen et al. 1980

Cohen, R.S., H. Cong, T.M. Dame, and P. Thaddeus, 1980: Molecular clouds and galactic spiral structure. Astrophys. J., 239, L53-L56, doi:10.1086/183290.

Two large-scale 2.6 mm CO surveys of the galactic plane, one in the first quadrant (l = 12° to 60°, b = -1° to +1°), the other in the second (l = 105° to 139°, b = -3° to +3°), have provided evidence that, contrary to previous findings, molecular clouds constitute a highly specific tracer of spiral structure. Molecular counterparts of five of the classical 21-cm spiral arms have been identified: the Perseus arm, the local arm (including Lindblad's local expanding ring), the Sagittarius arm, the Scutum arm, and the 4-kpc arm. The region between the local arm and the Perseus arm is apparently devoid of molecular clouds, and the interarm regions of the inner Galaxy appear largely so. CO spiral structure implies that the mean lifetime of molecular clouds cannot be greater than 1×108 years, the time required for interstellar matter to cross a spiral arm. Conservation of mass then sets a limit on the fraction of the interstellar medium in the form of molecular clouds: it cannot exceed one-half at any distance from the galactic center in the range 4-12 kpc.

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BibTeX Citation

@article{co04000r,
  author={Cohen, R. S. and Cong, H. and Dame, T. M. and Thaddeus, P.},
  title={Molecular clouds and galactic spiral structure},
  year={1980},
  journal={Astrophysical Journal},
  volume={239},
  pages={L53--L56},
  doi={10.1086/183290},
}

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RIS Citation

TY  - JOUR
ID  - co04000r
AU  - Cohen, R. S.
AU  - Cong, H.
AU  - Dame, T. M.
AU  - Thaddeus, P.
PY  - 1980
TI  - Molecular clouds and galactic spiral structure
JA  - Astrophys. J.
JO  - Astrophysical Journal
VL  - 239
SP  - L53
EP  - L56
DO  - 10.1086/183290
ER  -

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