Cosmic rays may provide the energy flux necessary for the continual synthesis of molecules in dense clouds, according to this detailed model of the carbon, oxygen, hydrogen and nitrogen chemistry of those regions.
The expanding universe is old and has a radius of light years or Matter in the universe, distributed in a highly non‐uniform manner, is concentrated largely in galaxies, which occupy only a minute fraction of the volume of the universe. In addition to stars, most galaxies contain diffuse, low density interstellar matter. Because interstellar matter is most easily studied in our own galaxy, the discussion here will focus on it, although this discussion should be pertinent to other galaxies as well.
This article is only available in PDF format
References
1. An excellent survey of the interstellar medium is given in L. Spitzer, Jr, “Diffuse Matter in Space,” Interscience, New York (1968).
2. D. M. Rank, C. H. Townes, W. J. Welch, Science 174, 1083 (1971).https://doi.org/SCIEAS
4. P. M. Solomon, PHYSICS TODAY, March 1973, page 32.
5. For HCO+ see: L. E. Snyder, D. Buhl, Nature 227, 862 (1970); https://doi.org/NATUAS L. E. Snyder, J. M. Hollis, B. L. Ulich, F. J. Lovas, D. Buhl, Bull. Am. Astron. Soc. 7, 497 (1975). https://doi.org/AASBAR For HCO+ see: W. Klemperer, Nature 227, 1230 (1970); https://doi.org/NATUAS U. Wahlgren, B. Liu, P. K. Pearson, H. F. SchaeferIII, Nature Phys. Sci. 246, 4 (1973). https://doi.org/NPSCA6 For N2H+ see: P. Thaddeus, B. E. Turner, Astrophys. J. (Lett.) 201, L25 (1975); https://doi.org/AJLEAU S. Green, J. A. MontgomeryJr, P. Thaddeus, Astrophys. J. (Lett.) 193, L89 (1974).https://doi.org/AJLEAU
6. R. C. Woods, T. A. Dixon, R. J. Sayhally, P. G. Szanto, Phys. Rev. Lett. 35, 1269 (1975).https://doi.org/PRLTAO
7. A detailed survey of processes relevant to molecule formation is given by W. D. Watson, Lectures at the 1974 Les Houches Summer School for Theoretical Physics, Les Houches, France.
11. T. P. Stecher, D. A. Williams, Astrophys. J. (Lett.) 149, L29 (1967); D. J. Hollenbach, M. W. Werner, E. E. Salpeter, Astrophys. J. 163, 165 (1971); https://doi.org/ASJOAB M. Jura, Astrophys. J. 191, 375 (1974).https://doi.org/ASJOAB
13. See, for example, P. Aanestad, Astrophys. J. (Supp.) 25, 205 (1973); W. D. Watson, E. E. Salpeter, Astrophys. J. 174, 321 (1972); https://doi.org/ASJOAB W. D. Watson, E. E. Salpeter, 175, 659 (1972).https://doi.org/ASJOAB, Astrophys. J.
20. E. Herbst, D. K. Bohme, J. D. Payzant, H. I. Schiff, Astrophys. J. 201, 603 (1975).https://doi.org/ASJOAB
21. F. C. Fehsenfeld, W. Lindinger, A. L. Schmeltehopf, D. L. Albritton, E. E. Ferguson, J. Chem. Phys. 62, 2001 (1975).https://doi.org/JCPSA6
22. E. Herbst, Astrophys. J., in press, April 1976.
23. F. C. Fehsenfeld, D. B. Dunkin, E. E. Ferguson, Astrophys. J. (Lett.) 188, L43 (1974).https://doi.org/AJLEAU
24. A. Dalgarno, M. Oppenheimer, J. H. Black, Nature Phys. Sci. 245, 100 (1973).https://doi.org/NPSCA6
25. J. M. Campbell, B. A. Thrush, Trans. Faraday Soc. 64, 1265 (1968); https://doi.org/TFSOA4 L. F. Phillips, H. I. Schiff, J. Chem. Phys. 36, 1509 (1962).https://doi.org/JCPSA6
26. H. I. Schiff, R. S. Hemsworth, J. D. Payzant, D. K. Bohme, Astrophys. J. (Lett.) 191, L49 (1974).https://doi.org/AJLEAU
More about the Authors
Eric Herbst.
Department of Chemistry, College of William and Mary, Williamsburg, Virginia.
Amid growing investment in planetary-scale climate intervention strategies that alter sunlight reflection, global communities deserve inclusive and accountable oversight of research.
Although motivated by the fundamental exploration of the weirdness of the quantum world, the prizewinning experiments have led to a promising branch of quantum computing technology.
As conventional lithium-ion battery technology approaches its theoretical limits, researchers are studying alternative architectures with solid electrolytes.
November 10, 2025 10:22 AM
This Content Appeared In
Volume 29, Number 6
Get PT in your inbox
PT The Week in Physics
A collection of PT's content from the previous week delivered every Monday.
One email per week
PT New Issue Alert
Be notified about the new issue with links to highlights and the full TOC.
One email per month
PT Webinars & White Papers
The latest webinars, white papers and other informational resources.