Supernova SN 2011fe from an exploding carbon–oxygen white dwarf star



Type Ia supernovae have been used empirically as ‘standard candles’ to demonstrate the acceleration of the expansion of the Universe1,2,3 even though fundamental details, such as the nature of their progenitor systems and how the stars explode, remain a mystery4,5,6. There is consensus that a white dwarf star explodes after accreting matter in a binary system, but the secondary body could be anything from a main-sequence star to a red giant, or even another white dwarf. This uncertainty stems from the fact that no recent type Ia supernova has been discovered close enough to Earth to detect the stars before explosion. Here we report early observations of supernova SN 2011fe in the galaxy M101 at a distance7 from Earth of 6.4 megaparsecs. We find that the exploding star was probably a carbon–oxygen white dwarf, and from the lack of an early shock we conclude that the companion was probably a main-sequence star. Early spectroscopy shows high-velocity oxygen that slows rapidly, on a timescale of hours, and extensive mixing of newly synthesized intermediate-mass elements in the outermost layers of the supernova. A companion paper8 uses pre-explosion images to rule out luminous red giants and most helium stars as companions to the progenitor.

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Figure 1: PTF g-band image sequence of the field of M101 showing the appearance of SN 2011fe.
Figure 2: Spectra of SN 2011fe taken 1.5 d after the explosion.
Figure 3: Early photometry of SN 2011fe shows a parabolic rise and constrains the time of explosion.
Figure 4: Models and early data limit the radius of the exploding star of SN 2011fe.


  1. 1

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

    ADS  Article  Google Scholar 

  2. 2

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

    ADS  Article  Google Scholar 

  3. 3

    Sullivan, M. et al. SNLS3: constraints on dark energy combining the supernova legacy survey three-year data with other probes. Astrophys. J. 737, 102–121 (2011)

    ADS  Article  Google Scholar 

  4. 4

    Howell, D. A. Type Ia supernovae as stellar endpoints and cosmological tools. Nature Commun. 2, 350 (2011)

    ADS  Article  Google Scholar 

  5. 5

    Kasen, D., Röpke, F. K. & Woosley, S. E. The diversity of type Ia supernovae from broken symmetries. Nature 460, 869–872 (2009)

    ADS  CAS  Article  Google Scholar 

  6. 6

    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)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Shappee, B. J. & Stanek, K. Z. A new Cepheid distance to the giant spiral M101 based on image subtraction of Hubble Space Telescope/Advanced Camera for Surveys observations. Astrophys. J. 733, 124–149 (2011)

    ADS  Article  Google Scholar 

  8. 8

    Li, W. et al. Exclusion of a luminous red giant as a companion star to the progenitor of supernova SN 2011fe. Nature (this issue).

  9. 9

    Nugent, P. E. et al. Young type Ia supernova PTF11kly in M101. Astron. Telegr. 3581, 1 (2011)

    ADS  Google Scholar 

  10. 10

    Thomas, R. C., Nugent, P. E. & Meza, J. C. SYNAPPS: data-driven analysis for supernova spectroscopy. Publ. Astron. Soc. Pacif. 123, 237–248 (2011)

    ADS  Article  Google Scholar 

  11. 11

    Filippenko, A. V. Optical spectra of supernovae. Annu. Rev. Astron. Astrophys. 35, 309–355 (1997)

    ADS  CAS  Article  Google Scholar 

  12. 12

    Branch, D. et al. The Type I supernova 1981b in NGC 4536 - the first 100 days. Astrophys. J. 270, 123–125 (1983)

    ADS  CAS  Article  Google Scholar 

  13. 13

    Leibundgut, B. et al. Premaximum observations of the type IA SN 1990N. Astrophys. J. 371, L23–L26 (1991)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Nugent, P., Phillips, M., Baron, E., Branch, D. & Hauschildt, P. Evidence for a spectroscopic sequence among type 1a supernovae. Astrophys. J. 455, L147–L151 (1995)

    ADS  CAS  Article  Google Scholar 

  15. 15

    Kirshner, R. P. et al. SN 1992A: ultraviolet and optical studies based on HST, IUE, and CTIO observations. Astrophys. J. 415, 589–615 (1993)

    ADS  CAS  Article  Google Scholar 

  16. 16

    Patat, F. et al. The type IA supernova 1994D in NGC 4526: the early phases. Mon. Not. R. Astron. Soc. 278, 111–124 (1996)

    ADS  CAS  Article  Google Scholar 

  17. 17

    Hatano, K., Branch, D., Fisher, A., Baron, E. & Filippenko, A. V. On the high-velocity ejecta of the type Ia supernova SN 1994D. Astrophys. J. 525, 881–885 (1999)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Piro, A. L., Chang, P. & Weinberg, N. N. Shock breakout from type Ia supernova. Astrophys. J. 708, 598–604 (2010)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Kasen, D. Seeing the collision of a supernova with its companion star. Astrophys. J. 708, 1025–1031 (2010)

    ADS  Article  Google Scholar 

  20. 20

    Fryer, C. L. et al. Spectra of type Ia supernovae from double degenerate mergers. Astrophys. J. 725, 296–308 (2010)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Shen, K. J., Bildsten, L., Kasen, D. & Quataert, E. The long-term evolution of double white dwarf mergers. Preprint at 〈〉 (2011)

  22. 22

    Rau, A. et al. Exploring the optical transient sky with the Palomar Transient Factory. Publ. Astron. Soc. Pacif. 121, 1334–1351 (2009)

    ADS  Article  Google Scholar 

  23. 23

    Law, N. M. et al. The Palomar Transient Factory: system overview, performance, and first results. Publ. Astron. Soc. Pacif. 121, 1395–1408 (2009)

    ADS  Article  Google Scholar 

  24. 24

    Gal-Yam, A. et al. Real-time detection and rapid multiwavelength follow-up observations of a highly subluminous type II-P supernova from the Palomar Transient Factory survey. Astrophys. J. 736, 159–166 (2011)

    ADS  Article  Google Scholar 

  25. 25

    Bloom, J. S. et al. Automating discovery and classification of transients and variable stars in the synoptic survey era. Preprint at 〈〉 (2011)

  26. 26

    de Vaucouleurs, G. et al. Third Reference Catalogue of Bright Galaxies (Springer, 1991)

  27. 27

    Rabinak, I., Livne, E. & Waxman, E. Early emission from type Ia supernovae. Preprint at 〈〉 (2011)

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The PTF project is a scientific collaboration between the California Institute of Technology, Columbia University, Las Cumbres Observatory, the Lawrence Berkeley National Laboratory, the National Energy Research Scientific Computing Center, the University of Oxford and the Weizmann Institute of Science. The National Energy Research Scientific Computing Center, supported by the Office of Science of the US Department of Energy (DOE), provided staff, computational resources and data storage for this project. P.E.N. acknowledges support from the US DOE Scientific Discovery through Advanced Computing programme. M.S. acknowledges support from the Royal Society. J.S.B. and L.B. were supported by the National Science Foundation (NSF). The work of A.V.F. is funded by the NSF, the TABASGO Foundation, Gary and Cynthia Bengier, and the Richard and Rhoda Goldman Fund. A.G. thanks the ISF and BSF. The Liverpool Telescope is operated by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Some of the data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA; the observatory was made possible by the generous financial support of the W. M. Keck Foundation. We thank the staffs of the many observatories at which data were obtained for their assistance.

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P.E.N., M.S. and D.A.H. oversee the PTF programme on type Ia supernovae. P.E.N. oversaw the preparation of the manuscript. M.S., D.B., K.M., Y.-C.P., J.L. and P.J. performed and reduced the FRODOSpec observations. S.B.C., M.T.K., A.V.F. and J.M.S. obtained and reduced the Lick spectrum. G.W.M., A.W.H. and H.T.I. obtained the HIRES observations. S.B.C., J.S.B., S.R.K., M.M.K., N.M.L., E.O.O., R.M.Q. and D.P. assisted in the operation of the Palomar 48-inch telescope as part of the PTF collaboration. R.C.T. and J.E.T. performed the SYNAPPS analysis. D.K., L.B. and P.P. assisted with the theoretical interpretation of our observations. N.S., B.J.F., J.T.P., D.S., F.B.B., B.D., M.L.G., I.M.H., P.M., E.P., E.S.W. and A.G. assisted in follow-up observations of SN 2011fe.

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Correspondence to Peter E. Nugent.

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The authors declare no competing financial interests.

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Nugent, P., Sullivan, M., Cenko, S. et al. Supernova SN 2011fe from an exploding carbon–oxygen white dwarf star. Nature 480, 344–347 (2011).

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