Hostname: page-component-77c89778f8-vsgnj Total loading time: 0 Render date: 2024-07-17T17:52:49.188Z Has data issue: false hasContentIssue false
  • English
  • Français

Origin and Evolution of Contact Binaries of W UMa Type

Published online by Cambridge University Press:  12 April 2016

Timo Rahunen  and
Osmi Vilhu
Timo Rahunen
Affiliation:
Observatory and Astrophysics Laboratory, University of Helsinki, SF-00130 Helsinki 13, Finland
Osmi Vilhu
Affiliation:
Observatory and Astrophysics Laboratory, University of Helsinki, SF-00130 Helsinki 13, Finland

Abstract

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.

Using angular momentum loss estimates from single star studies, it is shown that detached binaries are good candidates as progenitors of contact binaries. Three theories constructed for contact binary evolution (DSC, TRO and AML, see Fig. 1) are discussed. The DSC and TRO theories require a contact binary formation mechanism which produces unequal components (fission) while the AML theory can start from equal components (initially detached binaries). In all theories the end-product is a single star.

The stability of unequal entropy models was studied using a formula (2) which couples the energy transfer with the depth of contact and with the entropy difference. The models experience cyclic behaviour on a time scale of 106-107 years (Fig. 2) and the contact never breaks even on the nuclear time scale. This is the important consequence of a formula of type (2). Similar behaviour (with similar formula) is expected also for TRO models and even for DSC models if the discontinuity can be preserved during one cycle period.

The DSC and TRO theories, which at first sight look quite different, are in fact complementary. The most probable contact binary theory is perhaps a suitable combination of all three. In this theory angular momentum loss is the new and important factor which may manifest itself in the UV- and X-ray activity observed in W UMa stars.

Type
Part III: Evolutionary Processes in Close Binary Systems
Information
International Astronomical Union Colloquium , Volume 69: Binary and Multiple Stars as Tracers of Stellar Evolution , 1982 , pp. 289 - 299
Copyright
Copyright © Reidel 1982

References

Biermann, P., Thomas, H.-C.: 1972, Astron. Astrophys. 16, 60 Google Scholar
Biermann, P., Thomas, H.-C.: 1973, Astron. Astrophys. 23, 55 Google Scholar
Bodenheimer, P.: 1978, Astrophys. J. 224, 488 Google Scholar
Bopp, B.W., Ruciński, S.M.: 1981, IAU Symp. No. 93, eds. Sugimoto, D., Lamb, D.Q., Schramm, D.N., D. Reidel Publ. Co., Dordrecht, p. 181 Google Scholar
Eggen, O.J.: 1961, Royal Obs. Bull., No. 31 Google Scholar
Eggen, O.J.: 1967, Mem. Roy. Astron. Soc. 70, 111 Google Scholar
Flannery, B.P.: 1976, Astrophys. J. 205, 217 Google Scholar
Hazlehurst, J., Refsdal, S., Stobbe, C.: 1977, Astron. Astrophys. 58, 47 Google Scholar
Hazlehurst, J., Refsdal, S.: 1980, Astron. Astrophys. 84, 200 Google Scholar
Huang, S.-S.: 1966, Astrophys. J. 29, 331 Google Scholar
Kraicheva, Z.T., Popova, E.I., Tutukov, A.V., Yungelson, L.R.: 1979, Astron. Zh. 56, 520 Google Scholar
Lubow, S.H., Shu, F.H.: 1977 ,Astrophys. J. 216, 517 Google Scholar
Lucy, L.B.: 1976, Astrophys. J. 205, 208 Google Scholar
Lucy, L.B.: 1977, Astron. J. 82, 1013 Google Scholar
Lucy, L.B., Ricco, E.: 1979, Astron. J. 84, 401 Google Scholar
Lucy, L.B., Wilson, R.E.: 1979, Astrophys. J. 231, 502 Google Scholar
Mestel, L.: 1968, Monthly Notices Roy. Astron. Soc. 138, 359 Google Scholar
Rahunen, T.: 1981a, Astron. Astrophys. (in press)Google Scholar
Rahunen, T.: 1981b, in preparationGoogle Scholar
Rahunen, T., Vilhu, O.: 1977, Astron. Astrophys. 56, 99 Google Scholar
Refsdal, S., Stabell, R.: 1981, Astron. Astrophys. 93, 297 Google Scholar
Robertson, J.A., Eggleton, P.P.: 1977, Monthly Notices Roy. Astron. Soc. 179, 359 Google Scholar
Roxburgh, I.W.: 1966, Astrophys. J. 143, 111 Google Scholar
Schatzman, E.: 1962 , Ann. Astrophys. 25, 18 Google Scholar
Shu, F.H.: 1980, IAU Symp. No. 88, eds. Plavec, M.J., Popper, D.M., Ulrich, R.K., D. Reidel Publ. Co., Dordrecht, p. 477 Google Scholar
Shu, F.H., Lubow, S.H., Anderson, L.: 1976, Astrophys. J. 209, 536 Google Scholar
Shu, F.H., Lubow, S.H., Anderson, L.: 1979, Astrophys. J. 229, 223 Google Scholar
Skumanich, A.: 1972, Astrophys. J. 171, 565 Google Scholar
Smith, M.A.: 1979, Publ. Astr. Soc. Pacific 91, 737 Google Scholar
Vilhu, O.: 1973, Astron. Astrophys. 26, 267 Google Scholar
Vilhu, O.: 1981a, Astrophys. Space Sci. 78, 401 Google Scholar
Vilh, O.: 1981b, in preparationGoogle Scholar
Vilhu, O., Rahunen, T.: 1980, IAU Symp. No. 88, eds. Plavec, M.J., Popper, D.M., Ulrich, R.K., D. Reidel Publ. Co., Dordrecht, p. 491 Google Scholar
Vilhu, O., Rahunen, T.: 1981, IAU Symp. No. 93, eds. Sugimoto, D., Lamb, D.Q., Schramm, D.N., D. Reidel Publ. Co., Dordrecht, p. 181 Google Scholar
Webbink, R.F.: 1976, Astrophys. J. 209, 829 Google Scholar