Binary Stars as the Source of the Far-UV Excess in Elliptical Galaxies

  • Zhanwen Han
  • Philipp Podsiadlowski
  • Anthony E. Lynas-Gray
Conference paper
Part of the Astrophysics and Space Science Proceedings book series (ASSSP)


The discovery of an excess of light in the far-ultraviolet (UV) spectrum in elliptical galaxies was a major surprise in 1969. While it is now clear that this UV excess is caused by an old population of hot helium-burning stars without large hydrogen-rich envelopes rather than young stars, their origin has remained a mystery. Here we show that these stars most likely lost their envelopes because of binary interactions, similar to the hot subdwarf population in our own Galaxy. This has major implications for understanding the evolution of the UV excess and of elliptical galaxies in general. In particular, it implies that the UV excess is not a sign of age, as had been postulated previously, and predicts that it should not be strongly dependent on the metallicity of the population.


Star Formation Binary Interaction Binary Star Young Star Elliptical Galaxy 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bressan, A., Chiosi, C., & Fagotto, F. 1994, ApJS, 94, 63CrossRefADSGoogle Scholar
  2. Brown, T. M., Ferguson, H. C., Davidsen, A. F., & Dorman, B. 1997, ApJ, 482, 685CrossRefADSGoogle Scholar
  3. Brown T. M., et al. 2003, ApJ, 584, L69CrossRefADSGoogle Scholar
  4. Bruzual, G., & Charlot, S. 1993, ApJ, 405, 538CrossRefADSGoogle Scholar
  5. Burstein, D., Bertola, F., Buson, L. M., Faber, S. M., & Lauer, T. R. 1988, ApJ, 328, 440CrossRefADSGoogle Scholar
  6. Calzetti, D., et al. 2000, ApJ, 533, 682CrossRefADSGoogle Scholar
  7. Deharveng, J.-M., Boselli, A., & Donas, J. 2002, A&A, 393, 843CrossRefADSGoogle Scholar
  8. Dorman, B., O’Connell, R. W., & Rood, R. T. 1995, ApJ, 442, 105CrossRefADSGoogle Scholar
  9. Ferguson, H. C.,et al. 1991, ApJ, 382, L69CrossRefADSGoogle Scholar
  10. Greggio, L., & Renzini, A. 1990, ApJ, 364, 35CrossRefADSGoogle Scholar
  11. Han, Z., Podsiadlowski, Ph., Maxted, P. F. L., Marsh, T. R., & Ivanova, N. 2002, MNRAS, 336, 449CrossRefADSGoogle Scholar
  12. Han, Z., Podsiadlowski, Ph., Maxted, P. F. L., & Marsh, T. R. 2003, MNRAS, 341, 669CrossRefADSGoogle Scholar
  13. Han, Z., Podsiadlowski, Ph., & Lynas-Gray, A. E. 2007, MNRAS, 380, 1098CrossRefADSGoogle Scholar
  14. Heber, U. 1986, A&A, 155, 33ADSGoogle Scholar
  15. Kaviraj, S., et al. 2007, ApJS, 173, 619CrossRefADSGoogle Scholar
  16. Kurucz, R. L. 1992, in The Stellar Populations of Galaxies, IAU Symp. 149, ed by B. Barbuy, A. Renzini (Kluwer, Dordrecht), pp. 225–232Google Scholar
  17. Lee, Y.-W. 1994, ApJ, 430, L113CrossRefADSGoogle Scholar
  18. Lejeune, T., Cuisinier, F., & Buser, R. 1997, A&AS, 125, 229CrossRefADSGoogle Scholar
  19. Lejeune, T., Cuisinier, F., & Buser, R. 1998, A&AS, 130, 65CrossRefADSGoogle Scholar
  20. Maxted, P. F. L., Heber, U., Marsh, T. R., & North, R. C. 2001, MNRAS, 326, 1391CrossRefADSGoogle Scholar
  21. O’Connell, R. W. 1999, ARA&A, 37, 603CrossRefADSGoogle Scholar
  22. Rich, R. M., et al. 2005, ApJ, 619, L107CrossRefADSGoogle Scholar
  23. Schawinski, K., et al. 2007, ApJS, 173, 512CrossRefADSGoogle Scholar
  24. Terlevich, A. I., & Forbes, D. A. 2002, MNRAS, 330, 547CrossRefADSGoogle Scholar
  25. Worthey, G. 1994, ApJS, 95, 107CrossRefADSGoogle Scholar
  26. Yi, S. K., Demarque, P., & Kim, Y.-C. 1997, ApJ, 482, 677CrossRefADSGoogle Scholar
  27. Yi, S. K., et al. 1999, ApJ, 513, 128CrossRefADSGoogle Scholar
  28. Zhang, F., Li, L., & Han, Z. 2005, MNRAS, 364, 503ADSGoogle Scholar

Copyright information

© Springer-Verlag New York 2009

Authors and Affiliations

  • Zhanwen Han
    • 1
  • Philipp Podsiadlowski
    • 2
  • Anthony E. Lynas-Gray
    • 2
  1. 1.National Astronomical Observatories / Yunnan Observatory, the Chinese Academy of SciencesChina
  2. 2.Department of PhysicsUniversity of OxfordOxfordUK

Personalised recommendations