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Discovery of the progenitor of the type Ia supernova 2007on


Type Ia supernovae are exploding stars that are used to measure the accelerated expansion of the Universe1,2 and are responsible for most of the iron ever produced3. Although there is general agreement that the exploding star is a white dwarf in a binary system, the exact configuration and trigger of the explosion is unclear4, which could hamper their use for precision cosmology. Two families of progenitor models have been proposed. In the first, a white dwarf accretes material from a companion until it exceeds the Chandrasekhar mass, collapses and explodes5,6. Alternatively, two white dwarfs merge, again causing catastrophic collapse and an explosion7,8. It has hitherto been impossible to determine if either model is correct. Here we report the discovery of an object in pre-supernova archival X-ray images at the position of the recent type Ia supernova (2007on) in the elliptical galaxy NGC 1404. Deep optical images (also archival) show no sign of this object. From this we conclude that the X-ray source is the progenitor of the supernova, which favours the accretion model for this supernova, although the host galaxy is older (6–9 Gyr) than the age at which the explosions are predicted in the accreting models.

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Figure 1: Images of the region around SN2007on.


  1. Riess, A. G. et al. Observational evidence from supernovae for an accelerating universe and a cosmological constant. Astron. J. 116, 1009–1038 (1998)

    Article  ADS  Google Scholar 

  2. Perlmutter, S. et al. Measurements of omega and lambda from 42 high-redshift supernovae. Astrophys. J. 517, 565–586 (1999)

    Article  ADS  Google Scholar 

  3. Nomoto, K., Thielemann, F.-K. & Yokoi, K. Accreting white dwarf models of Type I supernovae. III. Carbon deflagration supernovae. Astrophys. J. 286, 644–658 (1984)

    Article  CAS  ADS  Google Scholar 

  4. Hillebrandt, W. & Niemeyer, J. C. Type Ia supernova explosion models. Annu. Rev. Astron. Astrophys. 38, 191–230 (2000)

    Article  CAS  ADS  Google Scholar 

  5. Whelan, J. & Iben, I. Binaries and supernovae of type I. Astrophys. J. 186, 1007–1014 (1973)

    Article  CAS  ADS  Google Scholar 

  6. Nomoto, K. Accreting white dwarf models for type I supernovae. I. Presupernova evolution and triggering mechanisms. Astrophys. J. 253, 798–810 (1982)

    Article  CAS  ADS  Google Scholar 

  7. Iben, I. & Tutukov, A. V. Supernovae of type I as end products of the evolution of binaries with components of moderate initial mass (M not greater than about 9 solar masses). Astrophys. J. Suppl. 84, 335–372 (1984)

    Article  ADS  Google Scholar 

  8. Webbink, R. Double white dwarfs as progenitors of R Coronae Borealis stars and type I supernovae. Astrophys. J. 277, 355–360 (1984)

    Article  CAS  ADS  Google Scholar 

  9. van den Heuvel, E. P. J., Bhattacharya, D., Nomoto, K. & Rappaport, S. A. Accreting white dwarf models for CAL 83, CAL 87 and other ultrasoft X-ray sources in the LMC. Astron. Astroph. 262, 97–105 (1992)

    CAS  ADS  Google Scholar 

  10. Piersanti, L., Gagliardi, S., Iben, I. & Tornambé, A. Carbon–oxygen white dwarf accreting CO-rich matter. II. Self-regulating accretion process up to the explosive stage. Astrophys. J. 598, 1229–1238 (2003)

    Article  CAS  ADS  Google Scholar 

  11. Saio, H. & Nomoto, K. Inward propagation of nuclear-burning shells in merging C–O and He white dwarfs. Astrophys. J. 500, 388–397 (1998)

    Article  CAS  ADS  Google Scholar 

  12. Han, Z. & Podsiadlowski, P. The single-degenerate channel for the progenitors of type Ia supernovae. Mon. Not. R. Astron. Soc. 350, 1301–1309 (2004)

    Article  CAS  ADS  Google Scholar 

  13. Yungelson, L. R. in White Dwarfs: Cosmological and Galactic Probes (eds Sion, E., Vennes, S. & Shipman, H.) 163–173 (Springer, Dordrecht, 2005)

    Book  Google Scholar 

  14. Mannucci, F., Della Valle, M. & Panagia, N. Two populations of progenitors for type Ia supernovae? Mon. Not. R. Astron. Soc. 370, 773–783 (2006)

    Article  ADS  Google Scholar 

  15. Scannapieco, E. & Bildsten, L. The type Ia supernova rate. Astrophys. J. 629, 85–88 (2005)

    Article  ADS  Google Scholar 

  16. Leonard, D. C. Constraining the type Ia supernova progenitor: The search for hydrogen in nebular spectra. Astrophys. J. 670, 1275–1282 (2007)

    Article  CAS  ADS  Google Scholar 

  17. Mattila, S. et al. Early and late time VLT spectroscopy of SN 2001el—progenitor constraints for a type Ia supernova. Astron. Astrophys. 443, 649–662 (2005)

    Article  CAS  ADS  Google Scholar 

  18. Ruiz-Lapuente, P. The binary progenitor of Tycho Brahe's 1572 supernova. Nature 431, 1069–1072 (2004)

    Article  CAS  ADS  Google Scholar 

  19. Pollas, C. & Klotz, A. Supernova 2007on in NGC 1404. Central Bureau Electronic Telegrams 1121, (2007)

  20. Gal-Yam, A. et al. SN 2007on is probably a young type Ia event. Astron. Tel. 1263, (2007)

  21. Tonry, J. L. et al. The SBF survey of galaxy distances. IV. SBF magnitudes, colors, and distances. Astrophys. J. 546, 681–693 (2001)

    Article  ADS  Google Scholar 

  22. Immler, S. et al. Swift observations of SN 2007on. Astron. Tel. 1261, (2007)

  23. Hamuy, M. et al. The absolute luminosities of the Calan/Tololo type IA supernovae. Astron. J. 112, 2391–2397 (1996)

    Article  ADS  Google Scholar 

  24. Bregman, J. N., Temi, P. & Bregman, J. D. The ages of elliptical galaxies from infrared spectral energy distributions. Astrophys. J. 647, 265–275 (2006)

    Article  CAS  ADS  Google Scholar 

  25. Li, Z., Han, Z. & Zhang, F. Potential of colors for determining age and metallicity of stellar populations. Astron. Astrophys. 464, 853–857 (2007)

    Article  ADS  Google Scholar 

  26. Cowley, A. P. et al. Six supersoft X-ray binaries: System parameters and twin-jet outflows. Astrophys. J. 504, 854–865 (1998)

    Article  CAS  ADS  Google Scholar 

  27. Yoon, S.-C., Podsiadlowski, P. & Rosswog, S. Remnant evolution after a carbon–oxygen white dwarf merger. Mon. Not. R. Astron. Soc. 380, 933–948 (2007)

    Article  CAS  ADS  Google Scholar 

  28. Tutukov, A. V. & Yungelson, L. R. Double-degenerate semidetached binaries with helium secondaries: cataclysmic variables, supersoft X-ray sources, supernovae and accretion-induced collapses. Mon. Not. R. Astron. Soc. 280, 1035–1045 (1996)

    Article  CAS  ADS  Google Scholar 

  29. Luna, G. J. M. & Sokoloski, J. L. The nature of the hard-X-ray emitting symbiotic star RT Cru. Astrophys. J. 671, 741–747 (2007)

    Article  CAS  ADS  Google Scholar 

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We thank the Central Bureau for Astronomical Telegrams for providing a list of supernovae. This research has made use of data obtained from the Chandra Data Archive and software provided by the Chandra X-ray Center in the application package CIAO, and of Swift data obtained from the High Energy Astrophysics Science Archive Research Center, provided by NASA’s Goddard Space Flight Center. The observations from the NASA/ESA Hubble Space Telescope were obtained from the data archive at the Space Telescope Institute. We thank NOVA for support. G.N. is supported by an NWO VENI grant.

Author Contributions The authors have contributed equally to the paper.

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Correspondence to Rasmus Voss or Gijs Nelemans.

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Voss, R., Nelemans, G. Discovery of the progenitor of the type Ia supernova 2007on. Nature 451, 802–804 (2008).

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