Subdwarf B and O Stars: Which Evolutionary Pathways?

Conference paper
Part of the Astrophysics and Space Science Proceedings book series (ASSSP)


Hot subdwarf stars (spectral types subdwarf B and O) are long lived stars producing a large amount of UV radiation. This makes them excellent candidates to explain the UV radiation observed in old populations. However, the origin of both classes of hot subdwarfs is unclear. I review possible single star and binary channels. High resolution observations of hot subdwarfs taken in the course of the Supernova type Ia Progenitor surveY (SPY) are presented. The SPY observations are used for a systematic assessment of the frequency of close binaries among hot subdwarfs. Results are a high binary fraction among the subdwarf B stars – albeit not as high as in a previous investigation, but a very low binary frequency in helium-rich hot subdwarf O stars. Implications for the evolutionary status of hot subdwarfs are discussed.


Elliptical Galaxy Horizontal Branch Radial Velocity Variation Binary Channel Horizontal Branch Star 


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  1. Burstein, D., Bertola, F., Buson, L. M., & Faber, S. M., & Lauer, T. R. 1988, ApJ, 328, 440CrossRefADSGoogle Scholar
  2. Code, A. D. 1969, PASP, 81, 475CrossRefADSGoogle Scholar
  3. Code, A. D., & Welch, G. A. 1979, ApJ, 228, 95CrossRefADSGoogle Scholar
  4. Dorman, B., O’Connell, R. W., & Rood, R. T. 2003, ApJ, 591, 878CrossRefADSGoogle Scholar
  5. D’Cruz, N. L., Dorman, B., Rood, R. T., & O’Connell, R. W. 1996, ApJ, 466, 359CrossRefADSGoogle Scholar
  6. Dreizler, S., Heber, U., Werner, K., Moehler, S., & de Boer, K. S. 1990, A&A, 235, 234ADSGoogle Scholar
  7. Edelmann, H., Heber, U., Lisker, T., & Green, E. M. 2004, Ap&SS, 291, 315CrossRefADSGoogle Scholar
  8. Greggio L., & Renzini, A. 1990, ApJ, 364, 35CrossRefADSGoogle Scholar
  9. Han, Z., Podsiadlowski, P., Maxted, P. F. L., & Marsh, T. R. 2003, MNRAS, 341, 669CrossRefADSGoogle Scholar
  10. Han, Z., Podsiadlowski, P., Maxted, P. F. L., Marsh, T. R., & Ivanova, N. 2002, MNRAS, 336, 449CrossRefADSGoogle Scholar
  11. Heber, U. 1986, A&A, 155, 33ADSGoogle Scholar
  12. Iben, I. 1990, ApJ,352, 215CrossRefADSGoogle Scholar
  13. Kalirai, J. S. 2007, 15 th European Workshop on White Dwarfs. ASPC 372, ed. by R. Napiwotzki & M. R. Burleigh (ASP: San Francisco) pp. 90–95Google Scholar
  14. Liebert, J., Saffer, R. A., & Green, E. M. 1994, AJ, 107, 1408CrossRefADSGoogle Scholar
  15. Lisker, T., Heber, U., Napiwotzki, R., Christlieb, N., Reimers, D., & Homeier, D. 2004, Ap&SS, 291, 351CrossRefADSGoogle Scholar
  16. Lisker, T., Heber, U., Napiwotzki, R., et al. 2005, A&A, 430, 223CrossRefADSGoogle Scholar
  17. Maxted, P. F. L., Heber, U., Marsh, T. R., & North, R. C. 2001, MNRAS, 326, 1391CrossRefADSGoogle Scholar
  18. Morales-Rueda, L., Maxted, P. F. L., Marsh, T. R., North, R. C., & Heber, U. 2003, MNRAS, 338, 752CrossRefADSGoogle Scholar
  19. Napiwotzki, R., Christlieb, N., Drechsel, H., et al. 2001, Astron. Nachrichten, 322, 411CrossRefADSGoogle Scholar
  20. Napiwotzki, R., Christlieb, N., Drechsel, H., et al. 2003, The Messenger, 112, 25ADSGoogle Scholar
  21. Napiwotzki, R., Karl, C. A., Lisker, T., et al. 2004, Ap&SS, 291, 321CrossRefADSGoogle Scholar
  22. Richter, R. 2006, Kinematik Weiβer Zwerge und heiβer, unterleuchtkräftiger Sterne, Diploma thesis (Universität Erlangen–Nürnberg, Erlangen)Google Scholar
  23. Saffer, R. A., & Liebert, J. 1995, White Dwarfs, LNP 443, ed. by D. Koester & K. Werner (Springer: Berlin, Heidelberg, New York) pp. 221–231Google Scholar
  24. Saffer, R. A., Bergeron, P., Koester, D., & Liebert, J. 1994, ApJ, 432, 351CrossRefADSGoogle Scholar
  25. Saffer, R. A., Livio, M., & Yungelson, L. R. 1998, ApJ, 502, 394CrossRefADSGoogle Scholar
  26. Saio, H., & Jeffery, C. S. 2000, MNRAS, 213, 671CrossRefADSGoogle Scholar
  27. Stroeer, A., Heber, U., Lisker, T., et al. 2007, A&A, 462, 269CrossRefADSGoogle Scholar
  28. Thejll, P. Bauer, F., Saffer, R., et al. 1994, ApJ, 433, 819CrossRefADSGoogle Scholar
  29. Wesemael, F., Winget, D.E., Cabot, W., van Horn, H.M., & Fontaine, G. 1982, ApJ, 254, 221CrossRefADSGoogle Scholar

Copyright information

© Springer-Verlag New York 2009

Authors and Affiliations

  1. 1.Centre for Astrophysics ResearchUniversity of HertfordshireHatfieldUK

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