Skip to main content
SpringerLink
Log in

Interstellar OH Excitation

  • Letter
  • Published:

From Nature

View current issue Submit your manuscript

Abstract

THERE are now many observations of the 18 cm radio emission from the OH molecules located at the edges of HII regions1. The high intensities, narrow bandwidths, and strong polarizations associated with the emission have led to the conclusion that it is stimulated emission in a collimated beam. The problem of explaining the emission then reduces to a description of the mechanism by which the upper levels in the masering state of the molecule are overpopulated with respect to a thermal distribution. The first suggestions were that the stellar ultraviolet radiation provides a pumping mechanism2,3. It has been pointed out1, however, that the ultraviolet cannot pump at the rate (∼1 cm−3 s−1) necessary for the brightest sources. As an alternative, Solomon4 has argued that because the OH is situated close to an HII region its lifetime must be short, so that overpopulation may be a result of the production mechanism. Here we discuss from this point of view a mechanism for the formation of OH recently proposed by us5.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Robinson, B. J., and McGee, R. X., Ann. Rev. Astro. Astrophys., 5, 183 (1967).

    Article  ADS  CAS  Google Scholar 

  2. Perkins, F., Gold, T., and Salpeter, E. E., Astrophys. J., 145, 361 (1966).

    Article  ADS  CAS  Google Scholar 

  3. Litvak, M. M., McWhorter, A. L., Meeks, M. L., and Zeiger, H. J., Phys. Rev. Lett., 17, 821 (1966).

    Article  ADS  CAS  Google Scholar 

  4. Solomon, P. M., Nature, 217, 334 (1968).

    Article  ADS  CAS  Google Scholar 

  5. Stecher, T. P., and Williams, D. A., Astrophys. J., 146, 88 (1966).

    Article  ADS  CAS  Google Scholar 

  6. Kondrat'ev, V. N., Chemical Kinetics of Gas Reactions (Pergamon Press, Oxford, 1964).

    Google Scholar 

  7. Polanyi, J. C., J. Chem. Phys., 31, 1338 (1959).

    Article  ADS  CAS  Google Scholar 

  8. Smith, F. T., J. Chem. Phys., 31, 1352 (1959).

    Article  ADS  CAS  Google Scholar 

  9. Kuntz, P. J., Nemeth, E. M., Polanyi, J. C., Rosner, S. D., and Young, C. E., J. Chem. Phys., 44, 1168 (1966).

    Article  ADS  CAS  Google Scholar 

  10. Herzberg, G., Spectra of Diatomic Molecules (Van Nostrand, Princeton, 1950).

    Google Scholar 

  11. Phelps, D. H., and Dalby, F. W., Canad. J. Phys., 43, 144 (1965).

    Article  ADS  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. NASA—Goddard Space Flight Center, Greenbelt, Maryland

    THEODORE P. STECHER

  2. Department of Mathematics, University of Manchester Institute of Science and Technology,

    DAVID A. WILLIAMS

Authors
  1. THEODORE P. STECHER
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. DAVID A. WILLIAMS
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

STECHER, T., WILLIAMS, D. Interstellar OH Excitation. Nature 219, 1138–1139 (1968). https://doi.org/10.1038/2191138a0

Download citation

  • Received:

  • Issue Date:

  • DOI: https://doi.org/10.1038/2191138a0

  • Springer Nature Limited

Search

Navigation