Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-25T15:38:43.831Z Has data issue: false hasContentIssue false

What are LBV’s? — Their characteristics and role in the upper H-R diagram

Published online by Cambridge University Press:  12 April 2016

Roberta M. Humphreys*
Affiliation:
Landessternwarte Heidelberg, and University of Minnesota

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Only ten years ago a symposium on the special class of stars we now call Luminous Blue Variables (LBV’s) would not have been possible. At that time we were only just beginning to recognize the similarities among the stars we call S Doradus variables, P Cygni stars, and Hubble-Sandage variables, and their importance in the evolution of the most massive stars.

About a decade ago it became clear that the observed H-R diagram has an upper luminosity limit and that η Car, P Cyg, and S Dor are all near the temperature-dependent boundary for hot stars. With hindsight the luminosity boundary can be seen in an H-R diagram for hot stars published by Hutchings (1976), but the full temperature range is necessary to show that it really exists. When more data became available in 1977—1978, including the evolved and cool supergiants, the upper luminosity limit became obvious; and we proposed that an instability causing rapid and unsteady mass loss (i.e., LBV’s) is the basic reason for this boundary (Humphreys and Davidson 1979). We emphasized the temperature-dependence of the boundary for the most luminous hot stars, the lack of cooler counterparts at similar luminosities, the nearly temperature-independent limit to the luminosities of cool hypergiants, and the critical role that objects like η Car, P Cyg, and S Dor may play in the evolution of the most massive stars.

Type
Section I: Main Papers, General Discussions, and Two Panel Discussions
Copyright
Copyright © Kluwer 1989

References

Allen, D.A., Jones, T.J., & Hyland, A.R. 1985, Astrophys.J. 291, 280.CrossRefGoogle Scholar
Appenzeller, I. 1986, IAU Symposium 116, Luminous Stars and Associations in Galaxies, p. 139.Google Scholar
Appenzeller, I., and Wolf, B. 1982, ESO Workshop on The Most Massive Stars, p. 131.Google Scholar
Bath, G.T. 1979, Nature 282, 173.CrossRefGoogle Scholar
Conti, P.S. 1984, IAU Symposium 105, Observational Tests of Stellar Evolution Theory, p. 233.Google Scholar
Davidson, K. 1987, Astrophys.J. 317, 760.CrossRefGoogle Scholar
Davidson, K., Dufour, R.J., Walborn, N.R., & Gull, T.R. 1986, Astrophys.J. 305, 867.CrossRefGoogle Scholar
Davidson, K., Walborn, N.R., & Gull, T.R. 1982, Astrophys.J.(Letters) 254, L47.CrossRefGoogle Scholar
de Jager, C. 1980, The Brightest Stars (Reidel: Dordrecht)CrossRefGoogle Scholar
de Jager, C. 1984, Astron.Astrophys. 138, 246.Google Scholar
Gallagher, J.S., Kenyon, S.J., & Hege, E.K. 1981, Astrophys.J. 249, 83.CrossRefGoogle Scholar
Hubble, E.P., & Sandage, A. 1953, Astrophys.J. 118, 353.CrossRefGoogle Scholar
Humphreys, R.M. 1975, Astrophys.J. 200, 426.CrossRefGoogle Scholar
Humphreys, R.M. 1978, Astrophys.J. 219, 445.CrossRefGoogle Scholar
Humphreys, R.M., Blaha, C., D’Odorico, S., Gull, T.R., & Benvenuti, P. 1984, Astrophys.J. 278, 124.CrossRefGoogle Scholar
Humphreys, R.M., & Davidson, K. 1979, Astrophys.J. 232, 409.CrossRefGoogle Scholar
Humphreys, R.M., & Davidson, K. 1984, Science 223, 243.CrossRefGoogle Scholar
Humphreys, R.M., Jones, T.J., & Gehrz, R.D. 1987, Astron.J. 94, 315.CrossRefGoogle Scholar
Humphreys, R.M., Leitherer, C., Stahl, O., Wolf, B., & Zickgraf, F.J. 1988, Astron.Astrophys. 203, 306.Google Scholar
Hutchings, J.B. 1976, Astrophys.J. 203, 438.CrossRefGoogle Scholar
Johnson, H.M. 1976, Astrophys.J. 206, 469.CrossRefGoogle Scholar
Kenyon, S.J., & Gallagher, J.S. 1985, Astrophys.J. 290, 542.CrossRefGoogle Scholar
Lamers, H.J.G.L.M. 1986, IAU Symposium 116, Luminous Stars and Associations in Galaxies, p. 157.Google Scholar
Lamers, H.J.G.L.M., & Fitzpatrick, E. 1988, Astrophys.J. 324, 279.CrossRefGoogle Scholar
Leitherer, C., Appenzeller, I., Klare, G., Lamers, H.J.G.L.M., Stahl, O., Waters, L.B.F.M., & Wolf, B. 1985 Astron.Astrophys. 153, 168.Google Scholar
Maeder, A. 1983, Astron.Astrophys. 120, 113.Google Scholar
McGregor, P.J., Hyland, A.R., & Hillier, D.J. 1988, Astrophys.J. 324, 1071.Google Scholar
Rosino, L., & Bianchini, A. 1973, Astron.Astrophys. 22, 953.Google Scholar
Sandage, A. 1983, Astron.J. 88, 1569.Google Scholar
Sandage, A. 1984, Astron.J. 89, 621.CrossRefGoogle Scholar
Stahl, O. 1986, Astron.Astrophys. 164, 321.Google Scholar
Stahl, O. 1987, Astron.Astrophys. 182, 229.Google Scholar
Stahl, O., & Wolf, B. 1986, Astron.Astrophys. 154, 243.Google Scholar
Stahl, O., Wolf, B., Leitherer, C., Zickgraf, F.-J., Krautter, J., & de Groot, M. 1984, Astron.Astrophys. 140, 459.Google Scholar
Stahl, O., Wolf, B., & Zickgraf, F.-J. 1987, Astron.Astrophys. 184, 193.Google Scholar
Stothers, R., & Chin, C. 1983, Astrophys.J. 264, 583.CrossRefGoogle Scholar
Tammann, G.A., & Sandage, A. 1968, Astrophys.J. 151, 831.CrossRefGoogle Scholar
Thackeray, A.D. 1977, Mon.Not. Roy. Astron. Soc. 180, 95.CrossRefGoogle Scholar
van Genderen, A.M., Steemers, W.J.G., Feldbrugge, P.T.M., de Groot, M., Damin, E., & van den Boogaart, A.K. 1985, Astron. Astrophys. 153, 163.Google Scholar
Walborn, N.R. 1977, Astrophys.J. 215, 53.CrossRefGoogle Scholar
Walborn, N.R. 1982, Astrophys.J. 256, 452.CrossRefGoogle Scholar
Walborn, N.R. 1985, IAU Symposium 116, Luminous Stars and Associations in Galaxies, p. 185.Google Scholar
Walborn, N.R. 1988, IAU Colloquium 108, Atmospheric Diagnostics of Stellar Evolution, p. 70.Google Scholar
Westphal, J.A., & Neugebauer, G. 1969, Astrophys. J.(Letters) 156, L45.CrossRefGoogle Scholar
Wolf, B., Appenzeller, I., & Stahl, O. 1981, Astron. Astrophys. 103, 94.Google Scholar
Wolf, B., & Stahl, O. 1982, Astron.Astrophys. 112, 111.Google Scholar
Zickgraf, F.-J., Wolf, B., Stahl, O., Leitherer, C., & Appenzeller, I. 1986, Astron. Astrophys. 163, 119.Google Scholar
Zickgraf, F.-J., Wolf, B., Stahl, O., Leitherer, C., & Klare, G. 1985, Astron. Astrophys. 143, 421.Google Scholar