Advertisement

Astrophysics and Space Science

, Volume 75, Issue 2, pp 341–351 | Cite as

Time-dependent chemistry in expanding circumstellar envelopes

  • P. V. Jameson
  • D. A. Williams
Article

Abstract

The rate equations of a restricted set of gas-phase chemical reactions occuring in an expanding circumstellar envelope are integrated numerically on the assumption that no chemical evolution has occurred in the stellar atmosphere. Abundances of all species are found to peak at a time on the order ofr0/u0, wherer0 is the initial radius andu0 the expansion velocity. After this time geometrical dilution dominates. For an initial density of 108 cm−3, on the order of 1% of hydrogen is converted to H2, and CH and CO have comparable densities of ∼10−6 relative to H, OH and O2 remain very low in abundance. For higher initial densities, H and H2 are more nearly comparable, and nearly all carbon is in CO, CH, OH and O2 remain low in abundance. The relevance of these results to M giants and other objects is discussed.

Keywords

Hydrogen Atmosphere Rate Equation Initial Density Chemical Evolution 
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.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Allen, C. W.: 1973,Astrophysical Quantities, (3rd ed) Athlone Press, London.Google Scholar
  2. Bardsley, J. M. and Biondi, M. A.: 1970,Adv. Atom. Mol. Phys. 6, 1.Google Scholar
  3. Barsuhn, J.: 1973,Astron. Astrophys. Suppl. 28, 453.Google Scholar
  4. Bates, D. R. and Dalgarno, A.: 1962, in D. R. Bates (ed.),Atomic and Molecular Processes, Academic Press, New York, p. 245.Google Scholar
  5. Conti, P. S.: 1978,Ann. Rev. Astron. Astrophys. 16, 371.Google Scholar
  6. Dalgarno, A. and McCray, R. A.: 1972,Ann. Rev. Astron. Astrophys. 10, 375.Google Scholar
  7. Dalgarno, A., Oppenheimer, N., and Berry, R. S.: 1973,Astrophys. J. 183, L21.Google Scholar
  8. Donn, B. D., Wickramasinghe, N. C., Hudson, J., and Stecher, T. P.: 1968,Astrophys. J. 153, 451.Google Scholar
  9. Field, G. B. and Steigman, G.: 1971,Astrophys. J. 166, 59.Google Scholar
  10. Fix, J. D. and Alexander, D. R.: 1974,Astrophys. J. 188, L91.Google Scholar
  11. Fusi-Pecci, F. and Renzini, A.: 1975,Mém. Soc. Roy. Sci. Liège 6th Ser. 8, 383.Google Scholar
  12. Hagen, W.: 1978,Astrophys. J. Suppl. 38, 1.Google Scholar
  13. Herbst, E. and Klemperer, W.: 1973,Astrophys. J. 185, 505.Google Scholar
  14. Herbst, E., Schubert, J. G., and Certain, P. R.: 1977,Astrophys. J. 213, 696.Google Scholar
  15. Hill, J. K. and Silk, J.: 1975,Astrophys. J. 202, L97.Google Scholar
  16. Hoyle, F. and Wickramasinghe, N. C.: 1977,Nature 270, 701.Google Scholar
  17. Hoyle, F., Solomon, P. M., and Woolf, N. J.: 1973,Astrophys. J. 185, L89.Google Scholar
  18. Jennings, M. C.: 1973,Astrophys. J. 185, 197.Google Scholar
  19. Johnson, H. R., Beebe, R. F., and Sneden, C.: 1975,Astrophys. J. Suppl. 29, 123.Google Scholar
  20. Kaler, J. B.: 1980,Nature 285, 439.Google Scholar
  21. Knapp, G. R., Kuiper, T. B. H., and Zuckerman, B.: 1979,Astrophys. J. 233, 140.Google Scholar
  22. Kwok, S.: 1975,Astrophys. J. 198, 583.Google Scholar
  23. McCabe, E. M., Connon Smith, R., and Clegg, R. E. S.: 1980, in B. H. Andrew (ed.), Interstellar Molecules',IAU Symp. 87, 497.Google Scholar
  24. Mitchell, G. F., Ginsburg, J. L., and Kuntz, P. J.: 1978,Astrophys. J. Suppl. 38, 39.Google Scholar
  25. Morris, S. and Wyller, A. A.: 1967,Astrophys. J. 150, 877.Google Scholar
  26. Pickles, J. B. and Williams, D. A.: 1980, in preparation.Google Scholar
  27. Williams, D. A.: 1968,Astrophys. J. 151, 935.Google Scholar
  28. Williams, D. A.: 1980,J. de. Phys. 41, c3–225.Google Scholar
  29. Zuckerman, B., Palmer, P., Morris, M., Turner, B. E., Gilra, D. P., Bowers, P. F., Gilmore, W.: 1977,Astrophys. J. 211, L97.Google Scholar

Copyright information

© D. Reidel Publishing Co 1981

Authors and Affiliations

  • P. V. Jameson
    • 1
  • D. A. Williams
    • 1
  1. 1.Institute of Science and Technology, Mathematics DepartmentUniv. of ManchesterManchesterEngland

Personalised recommendations