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The Shapes and Supersonic Motions of Molecular Clouds

  • Jin Koda
Part of the Astrophysics and Space Science Proceedings book series (ASSSP)

The energy source and mechanism for driving the supersonic motions in molecular clouds remain unknown. The unknown driving mechanism must exert an influence on the shape of molecular clouds [5]. We analyzed a sample of more than 500 molecular clouds identified with the BU-FCRAO Galactic Ring Survey (YRS) data, and found that they are preferentially elongated along the Galactic plane. Their spin axes are randomly oriented; therefore, we conclude that the elongation is supported by internal velocity anisotropy, but not by spin. The mechanism for driving the supersonic velocity dispersion must also account for the preferred elongation. This excludes some suggested mechanism, such as stellar winds and supernovae, because they do not produce the systemic elongation. Driving energy is more likely to come from large-scale motions, such as Galactic rotation.

Keywords

Velocity Dispersion Position Angle Molecular Cloud Axis Ratio Stellar Wind 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Downes, D., Wilson, T. L., Bieging, J. & Wink, J.: A&A 40, 397 (1980)Google Scholar
  2. 2.
    Elmegreen, B. G. & Scalo, J.: ARA&A 42, 211 (2004)CrossRefADSGoogle Scholar
  3. 3.
    Jackson, J. M., Rathborne, J. M., Shah, R. Y., et al.: ApJS 163, 145 (2006)CrossRefADSGoogle Scholar
  4. 4.
    Jog, C. J. & Ostriker, J. P.: ApJ 328, 404 (1988)CrossRefADSGoogle Scholar
  5. 5.
    Koda, J., Sawada, T., Hasegawa, T., Scoville, N. Z.: ApJ 638, 191 (2006)CrossRefADSGoogle Scholar
  6. 6.
    Larson, B. R.: MNRAS 194, 809 (1981)ADSGoogle Scholar
  7. 7.
    Mac Low, M. -M. & Klessen, R. S.: Reviews of Modern Physics 76, 125 (2004)CrossRefADSGoogle Scholar
  8. 8.
    Mooney, T. J. & Solomon, P. M.: ApJ 334, L51 (1988)CrossRefADSGoogle Scholar
  9. 9.
    Norman, C. A. & Ferrara, A.: ApJ 467, 280 (1996)Google Scholar
  10. 10.
    Sanders, D. B., Scoville, N. Z. & Solomon, P. M.: ApJ 289, 373 (1985)CrossRefADSGoogle Scholar
  11. 11.
    Scoville, N. Z. & Good, J. C.: ApJ 339, 149 (1989)CrossRefADSGoogle Scholar
  12. 12.
    Scoville, N. Z., Polletta, M., Ewald, S. Stolovy, S. R., Thompson, R. & Rieke, M.: AJ 122, 3017 (2001)CrossRefADSGoogle Scholar
  13. 13.
    Sellwood, J. A. & Balbus, S. A.: ApJ 511, 660 (1999)CrossRefADSGoogle Scholar
  14. 14.
    Wada, K., Meurer, G. & Norman, C. A.: ApJ 577, 197 (2002)CrossRefADSGoogle Scholar
  15. 15.
    Williams, J. P. & Blitz, L.: 494, 657 (1998)Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Jin Koda
    • 1
  1. 1.California Institute of TechnologyPasadenaUSA

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