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An extremely energetic supernova from a very massive star in a dense medium


The interaction of a supernova with a circumstellar medium (CSM) can dramatically increase the emitted luminosity by converting kinetic energy to thermal energy. In ‘superluminous’ supernovae of type IIn—named for narrow hydrogen lines1 in their spectra—the integrated emission can reach2,3,4,5,6 ~1051 erg, attainable by thermalizing most of the kinetic energy of a conventional supernova. A few transients in the centres of active galaxies have shown similar spectra and even larger energies7,8, but are difficult to distinguish from accretion onto the supermassive black hole. Here we present a new event, SN2016aps, offset from the centre of a low-mass galaxy, that radiated 5 × 1051 erg, necessitating a hyper-energetic supernova explosion. We find a total (supernova ejecta + CSM) mass likely exceeding 50−100 M, with energy 1052 erg, consistent with some models of pair-instability supernovae or pulsational pair-instability supernovae—theoretically predicted thermonuclear explosions from helium cores >50 M. Independent of the explosion mechanism, this event demonstrates the existence of extremely energetic stellar explosions, detectable at very high redshifts, and provides insight into dense CSM formation in the most massive stars.

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Fig. 1: Ground-based and HST images of SN2016aps and its host galaxy.
Fig. 2: Spectroscopic evolution of SN2016aps over 500 rest-frame days following discovery.
Fig. 3: Optical light curve of SN2016aps, compared with previous energetic SNe.
Fig. 4: Full light curves of SN2016aps and derived properties.

Data availability

All data are publicly available via the Open Supernova Catalog61 ( and the Weizmann Interactive SN Repository80 (

Code availability

MOSFiT is publicly available at SuperBol is publicly available at


  1. 1.

    Schlegel, E. M. A new subclass of type II supernovae? Mon. Not. R. Astron. Soc. 244, 269–271 (1990).

    ADS  Google Scholar 

  2. 2.

    Smith, N. et al. SN 2006gy: discovery of the most luminous supernova ever recorded, powered by the death of an extremely massive star like η Carinae. Astrophys. J. 666, 1116 (2007).

    ADS  Google Scholar 

  3. 3.

    Drake, A. et al. Discovery of the extremely energetic supernova 2008fz. Astrophys. J. 718, L127 (2010).

    ADS  Google Scholar 

  4. 4.

    Chatzopoulos, E. et al. SN 2008am: a super-luminous type IIn supernova. Astrophys. J. 729, 143 (2011).

    ADS  Google Scholar 

  5. 5.

    Rest, A. et al. Pushing the boundaries of conventional core-collapse supernovae: the extremely energetic supernova SN 2003ma. Astrophys. J. 729, 88 (2011).

    ADS  Google Scholar 

  6. 6.

    Benetti, S. et al. The supernova CSS121015:004244+132827: a clue for understanding superluminous supernovae. Mon. Not. R. Astron. Soc. 441, 289–303 (2014).

    ADS  Google Scholar 

  7. 7.

    Blanchard, P. K. et al. PS16dtm: a tidal disruption event in a narrow-line Seyfert 1 galaxy. Astrophys. J. 843, 106 (2017).

    ADS  Google Scholar 

  8. 8.

    Kankare, E. et al. A population of highly energetic transient events in the centres of active galaxies. Nat. Astron. 1, 865–871 (2017).

    ADS  Google Scholar 

  9. 9.

    Huber, M. et al. The Pan-STARRS Survey for Transients (PSST)—first announcement and public release. The Astronomer’s Telegram 7153 (2015).

  10. 10.

    Chornock, R. et al. Spectroscopic classification of two superluminous supernovae. The Astronomer’s Telegram 8790 (2016).

  11. 11.

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

    ADS  Google Scholar 

  12. 12.

    Dong, S. et al. ASASSN-15lh: a highly super-luminous supernova. Science 351, 257–260 (2016).

    ADS  Google Scholar 

  13. 13.

    Smith, N. et al. SN 2006tf: precursor eruptions and the optically thick regime of extremely luminous type IIn supernovae. Astrophys. J. 686, 467 (2008).

    ADS  Google Scholar 

  14. 14.

    Fransson, C. et al. High-density circumstellar interaction in the luminous type IIn SN 2010jl: the first 1100 days. Astrophys. J. 797, 118 (2014).

    ADS  Google Scholar 

  15. 15.

    Sukhbold, T. & Woosley, S. E. The most luminous supernovae. Astrophys. J. 820, L38 (2016).

    ADS  Google Scholar 

  16. 16.

    Chevalier, R. A. & Irwin, C. M. Shock breakout in dense mass loss: luminous supernovae. Astrophys. J. 729, L6 (2011).

    ADS  Google Scholar 

  17. 17.

    Chugai, N. N. & Danziger, I. J. SN 1988Z: low-mass ejecta colliding with the clumpy wind? Mon. Not. R. Astron. Soc. 268, 173–180 (1994).

    ADS  Google Scholar 

  18. 18.

    Chevalier, R. A. & Irwin, C. M. X-rays from supernova shocks in dense mass loss. Astrophys. J. 747, L17 (2012).

    ADS  Google Scholar 

  19. 19.

    Mackey, J. et al. Interacting supernovae from photoionization-confined shells around red supergiant stars. Nature 512, 282–285 (2014).

    ADS  Google Scholar 

  20. 20.

    Vink, J. S. Fast and slow winds from supergiants and luminous blue variables. Astron. Astrophys. 619, A54 (2018).

    ADS  Google Scholar 

  21. 21.

    Chatzopoulos, E., Wheeler, J. C. & Vinko, J. Generalized semi-analytical models of supernova light curves. Astrophys. J. 746, 121 (2012).

    ADS  Google Scholar 

  22. 22.

    Guillochon, J. et al. MOSFiT: modular open source fitter for transients. Astrophys. J. Suppl. 236, 6 (2018).

    ADS  Google Scholar 

  23. 23.

    Dessart, L., Audit, E. & Hillier, D. J. Numerical simulations of superluminous supernovae of type IIn. Mon. Not. R. Astron. Soc. 449, 4304–4325 (2015).

    ADS  Google Scholar 

  24. 24.

    Woosley, S. E. Pulsational pair-instability supernovae. Astrophys. J. 836, 244 (2017).

    ADS  Google Scholar 

  25. 25.

    Gomez, S. et al. SN 2016iet: the pulsational or pair instability explosion of a low-metallicity massive CO core embedded in a dense hydrogen-poor circumstellar medium. Astrophys. J. 881, 87 (2019).

    ADS  Google Scholar 

  26. 26.

    Vigna-Gómez, A., Justham, S., Mandel, I., de Mink, S. E. & Podsiadlowski, P. Massive stellar mergers as precursors of hydrogen-rich pulsational pair instability supernovae. Astrophys. J. 876, L29 (2019).

    ADS  Google Scholar 

  27. 27.

    Yan, L. et al. Hydrogen-poor superluminous supernovae with late-time Hα emission: three events from the intermediate Palomar Transient Factory. Astrophys. J. 848, 6 (2017).

    ADS  Google Scholar 

  28. 28.

    Lunnan, R. et al. A UV resonance line echo from a shell around a hydrogen-poor superluminous supernova. Nat. Astron. 2, 887–895 (2018).

    ADS  Google Scholar 

  29. 29.

    Chen, T. W. et al. SN 2017ens: the metamorphosis of a luminous broadlined type Ic supernova into an SN IIn. Astrophys. J. 867, L31 (2018).

    ADS  Google Scholar 

  30. 30.

    Kasen, D., Woosley, S. E. & Heger, A. Pair instability supernovae: light curves, spectra, and shock breakout. Astrophys. J. 734, 102 (2011).

    ADS  Google Scholar 

  31. 31.

    Chatzopoulos, E. & Wheeler, J. C. Hydrogen-poor circumstellar shells from pulsational pair-instability supernovae with rapidly rotating progenitors. Astrophys. J. 760, 154 (2012).

    ADS  Google Scholar 

  32. 32.

    Cooke, J. et al. Superluminous supernovae at redshifts of 2.05 and 3.90. Nature 491, 228–231 (2012).

    ADS  Google Scholar 

  33. 33.

    Martini, P. et al. The Ohio State Multi-object Spectrograph. Publ. Astron. Soc. Pac. 123, 187 (2011).

    ADS  Google Scholar 

  34. 34.

    Fabricant, D., Cheimets, P., Caldwell, N. & Geary, J. The FAST spectrograph for the tillinghast telescope. Publ. Astron. Soc. Pac. 110, 79–85 (1998).

    ADS  Google Scholar 

  35. 35.

    Schmidt, G. D., Weymann, R. J. & Foltz, C. B. A moderate-resolution, high-throughput CCD channel for the MMT spectrograph. Publ. Astron. Soc. Pac. 101, 713 (1989).

    ADS  Google Scholar 

  36. 36.

    Hook, I. M. et al. The Gemini-North Multi-Object Spectrograph: performance in imaging, long-slit, and multi-object spectroscopic modes. Publ. Astron. Soc. Pac. 116, 425–440 (2004).

    ADS  Google Scholar 

  37. 37.

    Oke, J. B. et al. The Keck low-resolution imaging spectrometer. Publ. Astron. Soc. Pac. 107, 375 (1995).

    ADS  Google Scholar 

  38. 38.

    Perley, D. A. Fully automated reduction of longslit spectroscopy with the low resolution imaging spectrometer at the Keck Observatory. Publ. Astron. Soc. Pac. 131, 084503 (2019).

    ADS  Google Scholar 

  39. 39.

    Schlafly, E. F. & Finkbeiner, D. P. Measuring reddening with Sloan Digital Sky Survey stellar spectra and recalibrating SFD. Astrophys. J. 737, 103 (2011).

    ADS  Google Scholar 

  40. 40.

    Planck Collaboration. et al Planck 2015 results. XIII. Cosmological parameters. Astron. Astrophys. 594, A13 (2016).

    Google Scholar 

  41. 41.

    Smith, N., Chornock, R., Silverman, J. M., Filippenko, A. V. & Foley, R. J. Spectral evolution of the extraordinary type IIn supernova 2006gy. Astrophys. J. 709, 856–883 (2010).

    ADS  Google Scholar 

  42. 42.

    Savitzky, A. & Golay, M. J. E. Smoothing and differentiation of data by simplified least squares procedures. Anal. Chem. 36, 1627–1639 (1964).

    ADS  Google Scholar 

  43. 43.

    Flewelling, H. et al. The Pan-STARRS1 Database and Data Products. Preprint at (2016).

  44. 44.

    Magnier, E.A. et al. The Pan-STARRS Data Processing System. Preprint at (2016).

  45. 45.

    Rahmer, G. et al. The 12Kx8K CCD mosaic camera for the Palomar Transient Factory. Proc. SPIE 7014, 70144Y (2008).

    Google Scholar 

  46. 46.

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

    ADS  Google Scholar 

  47. 47.

    Masci, F. J. et al. The IPAC Image Subtraction and Discovery Pipeline for the intermediate Palomar Transient Factory. Publ. Astron. Soc. Pac. 129, 014002 (2017).

    ADS  Google Scholar 

  48. 48.

    Ofek, E. O. et al. The Palomar Transient Factory photometric calibration. Publ. Astron. Soc. Pac. 124, 62–73 (2012).

    ADS  Google Scholar 

  49. 49.

    Brown, P. J. et al. Ultraviolet light curves of supernovae with the Swift ultraviolet/optical telescope. Astron. J. 137, 4517–4525 (2009).

    ADS  Google Scholar 

  50. 50.

    Breeveld, A. A. et al. An updated ultraviolet calibration for the Swift/UVOT. AIP Conf. Ser. 1358, 373–376 (2011).

    ADS  Google Scholar 

  51. 51.

    Lunnan, R. et al. Hydrogen-poor superluminous supernovae and long-duration gamma-ray bursts have similar host galaxies. Astrophys. J. 787, 138 (2014).

    ADS  Google Scholar 

  52. 52.

    Poznanski, D., Prochaska, J. X. & Bloom, J. S. An empirical relation between sodium absorption and dust extinction. Mon. Not. R. Astron. Soc. 426, 1465–1474 (2012).

    ADS  Google Scholar 

  53. 53.

    Inserra, C. et al. On the nature of hydrogen-rich superluminous supernovae. Mon. Not. R. Astron. Soc. 475, 1046–1072 (2018).

    ADS  Google Scholar 

  54. 54.

    Ofek, E. et al. SN 2006gy: an extremely luminous supernova in the galaxy NGC 1260. Astrophys. J. 659, L13 (2007).

    ADS  Google Scholar 

  55. 55.

    Agnoletto, I. et al. SN 2006gy: was it really extraordinary? Astrophys. J. 691, 1348 (2009).

    ADS  Google Scholar 

  56. 56.

    Miller, A. A. et al. SN 2008iy: an unusual type IIn supernova with an enduring 400-d rise time. Mon. Not. R. Astron. Soc. 404, 305–317 (2010).

    ADS  Google Scholar 

  57. 57.

    Moriya, T. J. et al. HSC16aayt: a slowly evolving interacting transient rising for more than 100 days. Astrophys. J. 882, 70 (2019).

    ADS  Google Scholar 

  58. 58.

    Tartaglia, L. et al. The long-lived type IIn SN 2015da: infrared echoes and strong interaction within an extended massive shell. Astron. Astrophys. 635, A39 (2019).

    Google Scholar 

  59. 59.

    Arcavi, I. et al. Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star. Nature 551, 210–213 (2017).

    ADS  Google Scholar 

  60. 60.

    Terreran, G. et al. Hydrogen-rich supernovae beyond the neutrino-driven core-collapse paradigm. Nat. Astron. 1, 713–720 (2017).

    ADS  Google Scholar 

  61. 61.

    Guillochon, J., Parrent, J., Kelley, L. Z. & Margutti, R. An open catalog for supernova data. Astrophys. J. 835, 64 (2017).

    ADS  Google Scholar 

  62. 62.

    Nicholl, M. SuperBol: A user-friendly Python routine for bolometric light curves. Res. Notes Am. Astron. Soc. 2, 230 (2018).

    ADS  Google Scholar 

  63. 63.

    Gall, C. et al. Rapid formation of large dust grains in the luminous supernova 2010jl. Nature 511, 326–329 (2014).

    ADS  Google Scholar 

  64. 64.

    Bhirombhakdi, K. et al. The type II superluminous SN 2008es at late times: near-infrared excess and circumstellar interaction. Mon. Not. R. Astron. Soc. 488, 3783–3793 (2019).

    ADS  Google Scholar 

  65. 65.

    Margutti, R. et al. Ejection of the massive hydrogen-rich envelope timed with the collapse of the stripped SN 2014C. Astrophys. J. 835, 140 (2017).

    ADS  Google Scholar 

  66. 66.

    Peng, C. Y., Ho, L. C., Impey, C. D. & Rix, H.-W. Detailed structural decomposition of galaxy images. Astron. J. 124, 266–293 (2002).

    ADS  Google Scholar 

  67. 67.

    Andrews, B. H. & Martini, P. The mass–metallicity relation with the direct method on stacked spectra of SDSS galaxies. Astrophys. J. 765, 140 (2013).

    ADS  Google Scholar 

  68. 68.

    Kennicutt, J. & Robert, C. Star formation in galaxies along the Hubble sequence. Annu. Rev. Astron. Astrophys. 36, 189–232 (1998).

    ADS  Google Scholar 

  69. 69.

    Lunnan, R. et al. Zooming in on the progenitors of superluminous supernovae with the HST. Astrophys. J. 804, 90 (2015).

    ADS  Google Scholar 

  70. 70.

    Sana, H. et al. Binary interaction dominates the evolution of massive stars. Science 337, 444 (2012).

    ADS  Google Scholar 

  71. 71.

    Paxton, B. et al. Modules for experiments in stellar astrophysics (MESA). Astrophys. J. Suppl. 192, 3 (2011).

    ADS  Google Scholar 

  72. 72.

    Paxton, B. et al. Modules for experiments in stellar astrophysics (MESA): convective boundaries, element diffusion, and massive star explosions. Astrophys. J. Suppl. 234, 34 (2018).

    ADS  Google Scholar 

  73. 73.

    Yoon, S. C., Langer, N. & Norman, C. Single star progenitors of long gamma-ray bursts. I. Model grids and redshift dependent GRB rate. Astron. Astrophys. 460, 199–208 (2006).

    ADS  Google Scholar 

  74. 74.

    de Mink, S. E., Langer, N., Izzard, R. G., Sana, H. & de Koter, A. The rotation rates of massive stars: the role of binary interaction through tides, mass transfer, and mergers. Astrophys. J. 764, 166 (2013).

    ADS  Google Scholar 

  75. 75.

    Nicholl, M., Guillochon, J. & Berger, E. The magnetar model for type I superluminous supernovae. I. Bayesian analysis of the full multicolor light-curve sample with MOSFiT. Astrophys. J. 850, 55 (2017).

    ADS  Google Scholar 

  76. 76.

    LSST Science Collaboration et al. LSST science book, version 2.0. Preprint at (2009).

  77. 77.

    Dessart, L., Hillier, D. J., Waldman, R., Livne, E. & Blondin, S. Superluminous supernovae: 56Ni power versus magnetar radiation. Mon. Not. R. Astron. Soc. 426, L76–L80 (2012).

    ADS  Google Scholar 

  78. 78.

    Jerkstrand, A., Smartt, S. J. & Heger, A. Nebular spectra of pair-instability supernovae. Mon. Not. R. Astron. Soc. 455, 3207–3229 (2016).

    ADS  Google Scholar 

  79. 79.

    Nicholl, M. et al. Slowly fading super-luminous supernovae that are not pair-instability explosions. Nature 502, 346–349 (2013).

    ADS  Google Scholar 

  80. 80.

    Yaron, O. & Gal-Yam, A. WISeREP—an interactive supernova data repository. Publ. Astron. Soc. Pac. 124, 668 (2012).

    ADS  Google Scholar 

  81. 81.

    Gal-Yam, A. et al. Supernova 2007bi as a pair-instability explosion. Nature 462, 624–627 (2009).

    ADS  Google Scholar 

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M.N. is a Royal Astronomical Society Research Fellow. The Berger Time-Domain Group acknowledge NSF grant AST-1714498 and NASA grant NNX15AE50G. R.L. acknowledges a Marie Skłodowska-Curie Individual Fellowship within the Horizon 2020 European Union Framework (H2020-MSCA-IF-2017-794467). W.-f.F. and K.P. acknowledge support from NSF grant numbers AST-1814782 and AST-1909358. The Margutti group acknowledges NSF grant number AST 1909796, NASA grants 80NSSC19K0384 and 80NSSC19K0646. A.A.M. is supported by the LSST Corporation, the Brinson Foundation, the Moore Foundation via the LSSTC Data Science Fellowship Program, and the CIERA Fellowship Program. A.V.-G. acknowledges support by the Danish National Research Foundation (DNRF132). Data were obtained via the NASA/ESA Hubble Space Telescope archive at the Space Telescope Science Institute, the Swift archive, the Smithsonian Astrophysical Observatory OIR Data Center, the MMT Observatory, the MDM Observatory, the Gemini Observatory, operated by the Association of Universities for Research in Astronomy, Inc., under agreement with the NSF, and the W.M. Keck Observatory, operated as a partnership among the California Institute of Technology, the University of California, and NASA. Operation of the Pan-STARRS1 telescope is supported by NASA under Grants NNX12AR65G and NNX14AM74G. The authors respect the very significant cultural role of Mauna Kea within the indigenous Hawaiian community.

Author information




M.N. wrote the manuscript, led the analysis and obtained the HST and Gemini data. P.K.B. devised the selection algorithm and identified SN2016aps as an interesting source, and analysed the HST images. E.B. advised on the manuscript and leads the overall project. R.C. and K.B. obtained the MDM spectrum and classified SN2016aps. R.M. analysed the UVOT data. P.K.B., S.G., A.B. and P.C. obtained FLWO data. R.L. obtained the Keck spectra. A.V.-G. did the rate calculations. A.A.M., F.J.M. and R.R.L. provided PTF data. W.-f.F. and P.K.B. obtained MMT imaging. G.T., A.A.M. and K.P. obtained Keck imaging. All authors helped with the interpretation.

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Correspondence to Matt Nicholl.

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Supplementary information

Extended Data Fig. 1 Bolometric light curve of SN2016aps.

Top: Comparison of the bolometric light curve to other SLSNe IIn. The integrated luminosity is greater than any previously known SN. Middle: Temperature evolution from blackbody fits (Methods). Bottom: Photospheric radius from blackbody fits. Error bars show 1σ uncertainties.

Extended Data Fig. 2 Fit to the light curve of SN2016aps with MOSFIT using a wind-like density profile.

(a) For fixed parameters based on simple scaling relations (see Supplementary Information). The fit is reasonable overall but systematically under-predicts the UV bands. (b) Realizations of a full MCMC fit. This matches the UV but favours masses larger by a factor ~ 3. Posteriors of the model parameters are given in Extended Data Fig. 3. Error bars show 1σ uncertainties.

Extended Data Fig. 3 Posteriors for physical parameters inferred using the MOSFIT CSM model.

Parameters are shown for fits using both shell (ρ=constant; black) and wind (ρ r−2; blue) density profiles. The additional variance (noise) parameter, σ ~ 0.1, indicates a similar quality of fit independent of the assumed density. Both models favour ejected masses 100M, with a comparable mass of CSM. Drawing from the joint Mej-vej posteriors gives a kinetic energy Ek ≈ 5 × 1052 erg in both cases.

Extended Data Fig. 4 Simulated observer frame LSST light curves in g,r,i,z bands.

The left column shows our interaction model for SN2016aps, while the right column shows a radioactively-powered PISN model for a 130 M helium core (Methods). The rows show the same models at redshifts z=0.1, 0.5, 0.75, 1 and 1.5. The interacting model is still well detected at z=1.5, because it is bright in the UV (whereas the radioactive model is heavily absorbed by metal lines). Therefore interacting events like SN2016aps are detectable over a volume that is larger by a factor 7. Error bars show simulated 1σ uncertainties.

Extended Data Fig. 5 Measurements of the Balmer lines.

The equivalent width of Hα increases over the first 300 days as the continuum fades, similar to other Type IIn SNe and SLSNe, before decreasing in the final epoch. The Hα/Hβ ratio is initially consistent with recombination (horizontal line), but at later times increases to >10, indicating collisional excitation. No Hβ could be measured in the final spectrum, the arrow indicates a lower limit on this ratio. Error bars show 1σ uncertainties.

Extended Data Fig. 6 Spectroscopic comparison of SN2016aps to the energetic nuclear transients PS16dtm and PS1-10adi.

PS16dtm is thought to be a TDE [7] and PS1-10adi has been suggested to be a possible SN close to an AGN [8], these two nuclear transients closely resemble each other. The spectra shown here are at around 200 days after maximum light. SN2016aps is distinguished from these events by broader and more symmetrical Balmer lines (lacking a red shoulder), and a lack of strong, narrow Fe II emission. SN2016aps also lacks the [O III] emission seen at 5000Å (see also Supplementary Information). The apparent absorption in PS16dtm at 7000Å is a telluric feature from the Earth’s atmosphere.

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Nicholl, M., Blanchard, P.K., Berger, E. et al. An extremely energetic supernova from a very massive star in a dense medium. Nat Astron 4, 893–899 (2020).

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