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Molecular Clouds in Spiral Galaxies

Published online by Cambridge University Press:  04 August 2017

Judith S. Young
Judith S. Young*
Affiliation:
Five College Radio Astronomy Observatory, U. of Massachusetts

Abstract

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A large observational program investigating the 2.6 mm CO line in spiral galaxies is being conducted by myself and Nick Scoville using the 14 m telescope of the Five College Radio Astronomy Observatory (HPBW = 50″). Thus far we have observed 46 galaxies of types Sa, Sb, Sc and Irr, detected 31, and mapped 16. Our major findings are:

  1. (1) In several late type spiral galaxies (IC 342, NGC 6946 and M51) the radial distribution of molecular gas out to 10 kpc follows the exponential blue luminosity profile of the disk within each galaxy (Young and Scoville 1982a, Scoville and Young 1983).

  2. (2) From a comparison of the CO and B luminosities of the central 5 kpc in a sample of Sc galaxies, we find that the blue luminosity is proportional to the first power of the CO content (Young and Scoville 1982b). We interpret this to mean that the star formation rate per H2in Sc galaxies (indicated by the B luminosity) is constant.

  3. (3) No molecular rings like the one in the Milky Way at radii 4 to 8 kpc were seen in the Sc galaxies.

  4. (4) We have found molecular rings in two Sb galaxies, NGC 7331 and NGC 2841, with peaks at radii of 4–5 kpc (Young and Scoville 1982c). The central holes in the CO distributions are possibly related to the presence of large nuclear bulges in these galaxies.

Type
I. Kinematics of Gas and the Underlying Mass Distribution
Information
Symposium - International Astronomical Union , Volume 100: Internal Kinematics and Dynamics of Galaxies , 1983 , pp. 49 - 52
Copyright
Copyright © Reidel 1983 

References

Ables, H.D.: 1971, Publ. U.S. Naval Obs. Sec. Ser., Vol XX, Part IV, Washington, D.C. Google Scholar
Boroson, T.: 1981, Astrophys. J. Supp., 46, 177.Google Scholar
Scoville, N.Z. and Young, J.S.: 1983, Astrophys. J., in press.Google Scholar
Young, J.S. and Scoville, N.Z.: 1982a, Astrophys. J., 258, 467.Google Scholar
Young, J.S. and Scoville, N.Z.: 1982b, Astrophys. J. (Letters), Sept. 1.Google Scholar
Young, J.S. and Scoville, N.Z.: 1982c, Astrophys. J. (Letters), Sept. 15.Google Scholar