Advertisement

Observational Connections Between LBV’S and Other Stars, With Emphasis On Wolf-Rayet Stars

  • A. F. J. Moffat
  • L. Drissen
  • C. Robert
Part of the Astrophysics and Space Science Library book series (ASSL, volume 157)

Abstract

We suggest that the LBV mechanism is an essential step to “force” massive stars (M(ZAMS) ≳ 40M ⊙) to finally enter the Wolf-Rayet (W-R) domain in the Hertzsprung-Russel diagram (HRD). Just as massive supergiants show increasing variability as they approach the Humphreys-Davidson (H-D) instability limit (horizontally in the HRD diagram), so the W-R stars show decreasing variability as they recede from the H-D limit (at first horizontally into the WNL domain, then, with their high mass loss rates, plunging irreversably downwards as ever hotter, smaller and fainter, strong-line W-R stars). Among the W-R stars, the luminous WNL subtypes (especially WN8) are the most variable, probably as a consequence of blob ejection in the wind. The underlying mechanism which triggers this ejection is possibly related to wind instabilities and may thus be quite different from the source of variability in luminous supergiants or LBV’s in quiescence, where photospheric effects dominate.

Keywords

Massive Star Luminous Star Luminous Blue Variable High Mass Loss Rate Clumpy Structure 
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. Abbott, D. C. 1982, Ap. J., 259, 282.ADSCrossRefGoogle Scholar
  2. Baade, D. 1988, in “O stars and Wolf-Rayet stars”, eds. P. S. Conti and A. B. Underhill, NASA SP-497, p. 137. Breysacher, J. 1986, Astron. Ap., 160, 185.Google Scholar
  3. Cherepashchuk, A. M., Eaton, J. A. and Khaliullin, Kh. F. 1984, Ap. J., 281, 774.ADSCrossRefGoogle Scholar
  4. Chu, Y. H., Treffers, R. R. and Kwitter, K. B. 1983, Ap. J. Suppl., 53, 937.ADSCrossRefGoogle Scholar
  5. Cox, A. N. and Cahn, J. H. 1988, Ap. J., 326, 804.ADSCrossRefGoogle Scholar
  6. Ensman, L. M. and Woosley, S. E. 1988, Ap. J., 333, 754.ADSCrossRefGoogle Scholar
  7. de Freitas-Pacheco, J. A. and Machado, M. A. 1988, A. J., 96, 365.ADSCrossRefGoogle Scholar
  8. Garmany, C. D., Conti, P. S. and Massey, P. 1980, Ap. J., 242, 1063.ADSCrossRefGoogle Scholar
  9. Hiltner, W. A. and Schild, R. E. 1966, Ap. J., 143, 770.ADSCrossRefGoogle Scholar
  10. van der Hucht, K. A., Hidayat, B., Admiranto, A. G., Supelli, K. R. and Doom, C. 1988, Astron. Ap., 199, 217. Humphreys, R. M. 1989, these proceedings.Google Scholar
  11. Humphreys, R. M., Nichols, M. and Massey, P. 1985, A. J., 90, 101.ADSCrossRefGoogle Scholar
  12. Koenigsberger, G. and Massey, P. 1989, these proceedings.Google Scholar
  13. Lamers, H. J. G. L. M. 1987, in “Instabilities in Luminous Early Type Stars”, eds. H. J. G. L. M. Lamers and C. W. H. de Loore, ( Reidel: Dordrecht ), p. 99.Google Scholar
  14. Lamontagne, R. and Moffat, A. F. J. 1987, A. J., 94, 1008.ADSCrossRefGoogle Scholar
  15. Leung, K. C., Moffat, A. F. J. and Seggewiss, W. 1983, Ap. J., 265, 961.ADSCrossRefGoogle Scholar
  16. Lortet, M.-C. and Testor, G. 1988, Astron. Ap., 194, 11.ADSGoogle Scholar
  17. Lundström, I. and Stenholm, B. 1984, Astron. Ap. Suppl. Ser., 58, 163.ADSGoogle Scholar
  18. Maeder, A. 1980, Astron. Ap., 90, 311.ADSGoogle Scholar
  19. Maeder, A. and Meynet, G. 1987, Astron. Ap., 182, 243.ADSGoogle Scholar
  20. Matthews, J. M. and Beech, M. 1987, Ap. J., 313, L25.ADSCrossRefGoogle Scholar
  21. Mc Candliss, S. R. and Bohannan, B. 1989, these proceedings.Google Scholar
  22. Moffat, A. F. J. 1981, in “Effects of Mass Loss in Stellar Evolution”, IAU Coll. No. 59, eds. C. Chiosi and R. Stalio, ( Reidel: Dordrecht ), p. 301.Google Scholar
  23. Moffat, A. F. J. 1982, in “Wolf-Rayet Stars: Observations, Physics, Evolution”, IAU Symp. No. 99, eds. C. W. H. de Loore and A. J. Willis ( Reidel: Dordrecht ), p. 515.Google Scholar
  24. Moffat, A. F. J. 1989, in preparation.Google Scholar
  25. Moffat, A. F. J., Vogt, N., Paquin, G., Lamontagne, R. and Barrera, L. H. 1986, A. J., 91, 1386.ADSCrossRefGoogle Scholar
  26. Moffat, A. F. J., Drissen, L., Lamontagne, R. and Robert, C. 1988, Ap. J., 334, 1038.ADSCrossRefGoogle Scholar
  27. Moffat, A. F. J., Niemela, V. S. and Marraco, H. 1989, Ap. J., submitted.Google Scholar
  28. Noels, A. and Scuflaire, R. 1987, in “Instabilities in Luminous Early Type Stars”, eds. H. J. G. L. M Lamers and C. W. H. de Loore, ( Reidel: Dordrecht ), p. 213.Google Scholar
  29. Owocki, S. P., Castor, J. I. and Rybicki, G. B. 1989, these proceedings.Google Scholar
  30. Robert, C., Drissen, L. and Moffat, A. F. J. 1989a, these proceedings.Google Scholar
  31. Robert, C., Moffat, A. F. J., Bastien, P., Drissen, L. and St.-Louis, N. 1989b, Ap. J., submitted.Google Scholar
  32. Schmutz, W. and Hamann, W.-R. 1986, Astron. Ap., 166, L11.ADSGoogle Scholar
  33. Smith, L. F. 1973, in “Wolf-Rayet and High Temperature Stars”, IAU Symp. No.Google Scholar
  34. Smith, L.F. and Hummer, D.G. 1988, M.N.R.A.S., 230, 511.Google Scholar
  35. Smith, L.F. and Maeder, A. 1988, preprint.Google Scholar
  36. Sybesma, C.H.B. 1986, Astron. Ap., 168, 147.ADSGoogle Scholar
  37. Torres, A.V. 1988, Ap. J., 325, 759.ADSCrossRefGoogle Scholar
  38. Vreux, J.-M. 1985, P.A.S.P., 97, 274.ADSCrossRefGoogle Scholar
  39. Walborn, N. 1974, Ap. J., 189, 269.ADSCrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1989

Authors and Affiliations

  • A. F. J. Moffat
    • 1
  • L. Drissen
    • 1
  • C. Robert
    • 1
  1. 1.Département de PhysiqueUniversité de MontréalMontréalCanada

Personalised recommendations