Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-23T19:10:36.105Z Has data issue: false hasContentIssue false
  • English
  • Français

An Ultraviolet Look at the Blue Edge of the ZZ Ceti Instability Strip

Published online by Cambridge University Press:  12 April 2016

R. Lamontagne ,
F. Vesemael ,
G. Fontaine ,
G. Vegner  and
E. P. Nelan
R. Lamontagne
Affiliation:
Département de Physique, Université de Montréal
F. Vesemael
Affiliation:
Département de Physique, Université de Montréal
G. Fontaine
Affiliation:
Département de Physique, Université de Montréal
G. Vegner
Affiliation:
Department of Physics and Astronomy, Dartmouth College
E. P. Nelan
Affiliation:
University of Texas/ S.T.Sc.I.

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.

It has already been shown that most, and probably all, of the DA white dwarfs become variable in a narrow temperature range as they cool down (Fontaine et al. 1982). Optical photometry and spectrophotometry has led to several determinations of the boundaries of this instability strip. The strip has been found to cover the range 10300 - 13600 K (McGraw 1979), 10400 - 12100 K (Greenstein 1982), 10000 - 13000 K (Weidemann and Koester 1984) and 11000 - 13000 K (Fontaine et al. 1985). Theoretical calculations show that the location of the blue edge is very sensitive to the efficiency of convection used in the unpertubed models (Winget et al. 1982; Winget and Fontaine 1982; Fontaine, Tassoul, and Wesemael 1984). Also, the sharpness of this boundary depends on the range of stellar mass and thickness of the hydrogen envelope found in ZZ Ceti stars. Recently, Wesemael, Lamontagne, and Fontaine (1986) and Lamontagne, Wesemael, and Fontaine (1987) have obtained and compared ultraviolet observations of several DA white dwarfs, in or near the instability strip, with published model calculations from Nelan and Wegner (1985), hereafter NW, and Koester et al. (1985), hereafter KWZV. They determined the boundaries of the variability region at 11400 - 12500 K or 11700 - 13000 K depending on which grid was used. We present here a reanalysis of these IUE observations with an improved grid of model atmospheres in order to define more precisely the location of the blue edge.

Type
Research Article
Information
International Astronomical Union Colloquium , Volume 114: White Dwarfs , 1989 , pp. 240 - 243
Copyright
Copyright © Springer-Verlag 1989

References

Bohlin, R.C. 1986, Astrophys. J., 308, 1001.CrossRefGoogle Scholar
Bohlin, R.C. and Grillmair, C.J. 1988, Astrophys. J. Supp., 66, 209.CrossRefGoogle Scholar
Bohlin, R.C. and Holm, A.V. 1980. MASA IUE Newsl. 10, 37.Google Scholar
Daou, D., Vesemael, F., Bergeron, P., Fontaine, G., and Holberg, J.B. 1988, these Proceedings.Google Scholar
Fontaine, G., Bergeron, P., Lacombe, P., Lamontagne, R., and Talon, A.. 1985, Astron. J., 90, 1094.CrossRefGoogle Scholar
Fontaine, G., McGraw, J.T., Dearborn, D.S.P., Gustafson, J., and Lacombe, P. 1982, Astrophys. J., 258, 651.CrossRefGoogle Scholar
Fontaine, G., Tassoul, M., and Vesemael, F. 1984, in Proceedings of the 25th Liège AstrophysicaJ Colloquium : TheoreticaJ Problems in Steller Stability and Oscillations, Noels, A. and Gabriel, M., eds., Université de Liège, p. 328.Google Scholar
Greenstein, J. L. 1982, Astrophys. J., 258, 661.CrossRefGoogle Scholar
Hackney, R.L., Hackney, K.R.H., and Kondo, Y. 1982, in Advances In Ultraviolet Astronomy: Four Years of IUE Research, NASA CP-2238 (NASA, Washington, DC), p. 335.Google Scholar
Koester, D., Weidemann, V., Zeidler K.-T., E. M., and Vauclair, G. 1985, Astron. Astrophys., 142, 5.Google Scholar
Lamontagne, R., Wesemael, F., and Fontaine, G. 1987, IAU Colloq. No. 95, The Second Conference on Faint Blue Stars, Davis Philip, A.G., Hayes, D.S., and Liebert, J.V., eds., L. Davis Press, p. 677.Google Scholar
McGraw, J.T. 1979, Astrophys. J., 229, 203.CrossRefGoogle Scholar
Nelan, E.P. and Wegner, G. 1985, Astrophys. J., 289, L31.CrossRefGoogle Scholar
Weidemann, V. and Koester, D. 1984, Astron. Astrophys., 132, 195.Google Scholar
Wesemael, F., Lamontagne, R., and Fontaine, G. 1986, Astron. J., 91, 1376.CrossRefGoogle Scholar
Winget, D.E. and Fontaine, G. 1982, in Pulsations in Classical and Cataclysmic Variable Stars, Cox, J.P. and Hansen, C.J., eds., Joint Institute for Laboratory Astrophysics, Boulder, p. 46.Google Scholar
Winget, D.E., van Horn, H.M., Tassoul, M., Hansen, C.J., Fontaine, G., and Carroll, B.W. 1982, Astrophys. J., 252, L65.CrossRefGoogle Scholar