Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen1,2. The uniformity of their light curves makes these supernovae powerful cosmological distance indicators3,4, but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved2,5,6. For example, the recent detection of the early ultraviolet pulse of a peculiar, subluminous type Ia supernova has been claimed as evidence for an interaction between a red-giant or a main-sequence companion and ejecta from a white-dwarf explosion7,8. Here we report observations of a prominent but red optical flash that appears about half a day after the explosion of a type Ia supernova. This supernova shows hybrid features of different supernova subclasses, namely a light curve that is typical of normal-brightness supernovae, but with strong titanium absorption, which is commonly seen in the spectra of subluminous ones. We argue that this early flash does not occur through previously suggested mechanisms such as the companion–ejecta interaction8,9,10. Instead, our simulations show that it could occur through detonation of a thin helium shell either on a near-Chandrasekhar-mass white dwarf, or on a sub-Chandrasekhar-mass white dwarf merging with a less-massive white dwarf. Our finding provides evidence that one branch of previously proposed explosion models—the helium-ignition branch—does exist in nature, and that such a model may account for the explosions of white dwarfs in a mass range wider than previously supposed11,12,13,14.
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Filippenko, A. V. Optical spectra of supernovae. Annu. Rev. Astron. Astrophys. 35, 309–355 (1997)
Maoz, D., Mannucci, F. & Nelemans, G. Observational clues to the progenitors of type Ia supernovae. Annu. Rev. Astron. Astrophys. 52, 107–170 (2014)
Perlmutter, S. et al. Measurements of Ω and Λ from 42 high-redshift supernovae. Astrophys. J. 517, 565–586 (1999)
Riess, A. G. et al. Observational evidence from supernovae for an accelerating universe and a cosmological constant. Astron. J. 116, 1009–1038 (1998)
Hillebrandt, W. & Niemeyer, J. C. Type Ia supernova explosion models. Annu. Rev. Astron. Astrophys. 38, 191–230 (2000)
Whelan, J. & Iben, I. Jr. Binaries and supernovae of type I. Astrophys. J. 186, 1007–1014 (1973)
Cao, Y. et al. A strong ultraviolet pulse from a newborn type Ia supernova. Nature 521, 328–331 (2015)
Kasen, D. Seeing the collision of a supernova with its companion star. Astrophys. J. 708, 1025–1031 (2010)
Levanon, N., Soker, N. & García-Berro, E. Constraining the double-degenerate scenario for type Ia supernovae from merger ejected matter. Mon. Not. R. Astron. Soc. 447, 2803–2809 (2015)
Piro, A. L. & Morozova, V. S. Exploring the potential diversity of early type Ia supernova light curves. Astrophys. J. 826, 96 (2016)
Bildsten, L., Shen, K. J., Weinberg, N. N. & Nelemans, G. Faint thermonuclear supernovae from AM Canum Venaticorum binaries. Astrophys. J. 662, L95–L98 (2007)
Fink, M. et al. Double-detonation sub-Chandrasekhar supernovae: can minimum helium shell masses detonate the core? Astron. Astrophys. 514, A53 (2010)
Woosley, S. E. & Kasen, D. Sub-Chandrasekhar mass models for supernovae. Astrophys. J. 734, 38 (2011)
Pakmor, R., Kromer, M., Taubenberger, S. & Springel, V. Helium-ignited violent mergers as a unified model for normal and rapidly declining type Ia supernovae. Astrophys. J. 770, L8 (2013)
Miyazaki, S. et al. Hyper Suprime-Cam. Proc. SPIE 8446, http://doi.org/10.1117/12.926844 (2012)
Guy, J. et al. SALT2: using distant supernovae to improve the use of type Ia supernovae as distance indicators. Astron. Astrophys. 466, 11–21 (2007)
Phillips, M. M. The absolute magnitudes of type IA supernovae. Astrophys. J. 413, L105–L108 (1993)
Pan, K., Ricker, P. M. & Taam, R. E. Impact of type Ia supernova ejecta on binary companions in the single-degenerate scenario. Astrophys. J. 750, 151 (2012)
Kutsuna, M. & Shigeyama, T. Revealing progenitors of type Ia supernovae from their light curves and spectra. Publ. Astron. Soc. Jpn 67, 54 (2015)
Nomoto, K., Thielemann, F.-K. & Yokoi, K. Accreting white dwarf models for type I supern. III. Carbon deflagration supernovae. Astrophys. J. 286, 644–658 (1984)
Khokhlov, A. M. Delayed detonation model for type IA supernovae. Astron. Astrophys. 245, 114–128 (1991)
Guillochon, J., Dan, M., Ramirez-Ruiz, E. & Rosswog, S. Surface detonations in double degenerate binary systems triggered by accretion stream instabilities. Astrophys. J. 709, L64–L69 (2010)
Kromer, M. et al. Double-detonation sub-Chandrasekhar supernovae: synthetic observables for minimum helium shell mass models. Astrophys. J. 719, 1067–1082 (2010)
Boyle, A., Sim, S. A., Hachinger, S. & Kerzendorf, W. Helium in double-detonation models of type Ia supernovae. Astron. Astrophys. 599, A46 (2017)
Noebauer, U. M. et al. Early light curves for type Ia supernova explosion models. Preprint at http://arxiv.org/abs/1706.03613 (2017)
Shen, K. J. & Bildsten, L. The ignition of carbon detonations via converging shock waves in white dwarfs. Astrophys. J. 785, 61 (2014)
Tanikawa, A. et al. Hydrodynamical evolution of merging carbon-oxygen white dwarfs: their pre-supernova structure and observational counterparts. Astrophys. J. 807, 40 (2015)
Nomoto, K., Sugimoto, D. & Neo, S. Carbon deflagration supernova, an alternative to carbon detonation. Astrophys. Space Sci. 39, L37–L42 (1976)
Blondin, S., Dessart, L., Hillier, D. J. & Khokhlov, A. M. Evidence for sub-Chandrasekhar-mass progenitors of type Ia supernovae at the faint end of the width–luminosity relation. Mon. Not. R. Astron. Soc. 470, 157–165 (2017)
Shen, K. J., Kasen, D., Miles, B. J. & Townsley, D. M. Sub-Chandrasekhar-mass white dwarf detonations revisited. Preprint at http://arxiv.org/abs/1706.01898 (2017)
Miyazaki, S. et al. Wide-field imaging with Hyper Suprime-Cam: cosmology and galaxy evolution. A strategic survey proposal for the Subaru telescope. http://hsc.mtk.nao.ac.jp/ssp/wp-content/uploads/2016/05/hsc_ssp_rv_jan13.pdf (2014)
Bolton, A. S. et al. Spectral classification and redshift measurement for the SDSS-III baryon oscillation spectroscopic survey. Astron. J. 144, 144 (2012)
Shimasaku, K. et al. Statistical properties of bright galaxies in the Sloan digital sky survey photometric system. Astron. J. 122, 1238–1250 (2001)
Peng, C. Y., Ho, L. C., Impey, C. D. & Rix, H.-W. Detailed decomposition of galaxy images. II. Beyond axisymmetric models. Astron. J. 139, 2097–2129 (2010)
Stetson, P. B. DAOPHOT: a computer program for crowded-field stellar photometry. Publ. Astron. Soc. Pacif. 99, 191–222 (1987)
Doi, M. et al. Photometric response functions of the Sloan digital sky survey imager. Astron. J. 139, 1628–1648 (2010)
Schlegel, D. J., Finkbeiner, D. P. & Davis, M. Maps of dust infrared emission for use in estimation of reddening and cosmic microwave background radiation foregrounds. Astrophys. J. 500, 525–553 (1998)
Maeda, K., Kutsuna, M. & Shigeyama, T. Signatures of a companion star in type Ia supernovae. Astrophys. J. 794, 37 (2014)
Fryer, C. L. et al. Spectra of type Ia supernovae from double degenerate mergers. Astrophys. J. 725, 296–308 (2010)
Shen, K. J., Bildsten, L., Kasen, D. & Quataert, E. The long-term evolution of double white dwarf mergers. Astrophys. J. 748, 35 (2012)
Levanon, N. & Soker, N. Early UV emission from disk-originated matter (DOM) in type Ia supernovae in the double degenerate scenario. Mon. Not. R. Astron. Soc. 470, 2510–2516 (2017)
Arnett, D. Supernovae and Nucleosynthesis: An Investigation of the History of Matter from the Big Bang to the Present (Princeton Univ. Press, 1996)
Kasen, D., Thomas, R. C. & Nugent, P. Time-dependent Monte Carlo radiative transfer calculations for three-dimensional supernova spectra, light curves, and polarization. Astrophys. J. 651, 366–380 (2006)
Kromer, M. & Sim, S. A. Time-dependent three-dimensional spectrum synthesis for type Ia supernovae. Mon. Not. R. Astron. Soc. 398, 1809–1826 (2009)
Sim, S. A. et al. Detonations in sub-Chandrasekhar-mass C+O white dwarfs. Astrophys. J. 714, L52–L57 (2010)
Shen, K. J. & Moore, K. The initiation and propagation of helium detonations in white dwarf envelopes. Astrophys. J. 797, 46 (2014)
Nugent, P., Phillips, M., Baron, E., Branch, D. & Hauschildt, P. Evidence for a spectroscopic sequence among type 1a supernovae. Astrophys. J. 455, L147–L150 (1995)
Piro, A. L. & Nakar, E. What can we learn from the rising light curves of radioactively powered supernovae? Astrophys. J. 769, 67 (2013)
Piro, A. L. & Nakar, E. Constraints on shallow 56Ni from the early light curves of type Ia supernovae. Astrophys. J. 784, 85 (2014)
Mazzali, P. A. et al. Hubble Space Telescope spectra of the type Ia supernova SN 2011fe: a tail of low-density, high-velocity material with Z < Z⊙ . Mon. Not. R. Astron. Soc. 439, 1959–1979 (2014)
Zheng, W. et al. Estimating the first-light time of the type Ia supernova 2014J in M82. Astrophys. J. 783, L24 (2014)
Nugent, P. E. et al. Supernova SN 2011fe from an exploding carbon-oxygen white dwarf star. Nature 480, 344–347 (2011)
Cao, Y. et al. SN2002es-like supernovae from different viewing angles. Astrophys. J. 832, 86 (2016)
Piro, A. L., Chang, P. & Weinberg, N. N. Shock breakout from type Ia supernova. Astrophys. J. 708, 598–604 (2010)
Yaron, O. & Gal-Yam, A. WISeREP—an interactive supernova data repository. Publ. Astron. Soc. Pacif. 124, 668–681 (2012)
Guillochon, J., Parrent, J., Kelley, L. Z. & Margutti, R. An open catalog for supernova data. Astrophys. J. 835, 64 (2017)
Maguire, K. et al. PTF10ops—a subluminous, normal-width light curve type Ia supernova in the middle of nowhere. Mon. Not. R. Astron. Soc. 418, 747–758 (2011)
Kromer, M. et al. SN 2010lp—a type Ia supernova from a violent merger of two carbon-oxygen white dwarfs. Astrophys. J. 778, L18 (2013)
Foley, R. J. et al. SN 2006bt: a perplexing, troublesome, and possibly misleading type Ia supernova. Astrophys. J. 708, 1748–1759 (2010)
Ganeshalingam, M. et al. Results of the Lick Observatory supernova search follow-up photometry program: BVRI light curves of 165 type Ia supernovae. Astrophys. J. Suppl. Ser. 190, 418–448 (2010)
Scalzo, R. et al. Type Ia supernova bolometric light curves and ejected mass estimates from the nearby supernova factory. Mon. Not. R. Astron. Soc. 440, 1498–1518 (2014)
Ciabattari, F. et al. Supernova 2012df = Psn J17481875+5218023. Central Bureau For Astronomical Telegrams No. 3161, http://www.cbat.eps.harvard.edu (2012)
Kromer, M. et al. The peculiar type Ia supernova iPTF14atg: Chandrasekhar-mass explosion or violent merger? Mon. Not. R. Astron. Soc. 459, 4428–4439 (2016)
Ganeshalingam, M. et al. The low-velocity, rapidly fading type Ia supernova 2002es. Astrophys. J. 751, 142 (2012)
Li, W. et al. SN 2002cx: the most peculiar known type Ia supernova. Publ. Astron. Soc. Pacif. 115, 453–473 (2003)
Foley, R. J. et al. Type Iax supernovae: a new class of stellar explosion. Astrophys. J. 767, 57 (2013)
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Extended data figures and tables
Extended Data Figure 1 Comparison of MUSSES1604D early-phase observations and the outcomes of different model simulations.
Shown are the observed g-band (purple filled circles), rest-frame B-band (purple open squares), V-band (light green open squares), and B–V (blue filled circles) curves for MUSSES1604D at flash phase. The red solid lines show the results from our best-fitting helium-detonation model (with a white dwarf (WD) of mass 1.38M⊙ and a helium shell of mass 0.03M⊙). a–c, Early B-band (a) and V-band (b) light curves and B−V colour evolution (c) generated by different CEI simulations observed from the companion side. Dashed lines correspond to K10 models involving different binary-system compositions (MS, main-sequence star; RG, red-giant star)8. The magenta line denotes our best-fitting K–S CEI model19. Although an early flash as bright as that of MUSSES1604D can be produced with specific CEI models, the predicted colour is very blue in the flash phase. d, e, V-band light curves simulated by CSM–ejecta interaction models (P16 model)10 with deep (d) and shallow (e) 56Ni distribution for the inner ejecta. Dotted lines correspond to an external mass (Me) of 0.3M⊙ with different outer radii, Re. f, Colour evolution, under the same assumptions as in e. Like the CEI models, the CSM–ejecta simulations generate combinations of early light curves and colour evolution that differ from the observed features of MUSSES1604D.
Spectra for MUSSES1604D (dark green) are compared with those of the analogous type Ia supernovae SN 2006bt, SN 2007cq and SN 2012df at similar epochs. Late-phase spectra of SN 2011fe are included for reference. SALT/Robert Stobie Spectrograph (RSS) follow-up observations were carried out −2 and 12 days after the B-band maximum, and the other two spectra were taken by the Gemini Multi-Object Spectrograph (GMOS) mounted on the Gemini-North telescope 3 and 26 days after the B-band maximum.
Extended Data Figure 3 Rest-frame B- and V-band light curves for MUSSES1604D and other type Ia supernovae.
K-corrections in the flash phase (open squares) and post-flash phase (filled squares with dashed lines) of MUSSES1604D were carried out with different methods (see Methods). The light curves of MUSSES1604D, SN 2006bt and SN 2007cq show an excellent match. Another peculiar early-flash type Ia supernova, iPTF14atg, also shows similar light curves, although its brightness is about one magnitude fainter than that of MUSSES1604D. The light curves of a normal-brightness type Ia supernova—SN 2011fe (black dotted lines)—are provided for reference. Magnitudes shown are in the Vega system; error bars denote 1σ uncertainties.
The left panel shows the earliest Subaru/HSC image of MUSSES1604D (α(J2000) = 12 h 18 min 19.85 s, δ(J2000) = +00° 15′ 17.38″) taken on 4.345 April 2016 ut, when the g-band magnitude of MUSSES1604D was 25.14 ± 0.15. The supernova then brightened rapidly to about 23.1 mag in one day (right panel).
We used the composition structures shown here in helium-detonation simulations with a sub-Chandrasekhar-mass white dwarf (a, c) or a Chandrasekhar-mass white dwarf (b, d). The mass fractions of selected elements are shown as a function of velocity (a, b) or mass coordinate (c, d). The colours are the same for all panels.
The density structures (as a function of velocity) shown here are the input models used for the radiation-transfer simulations, representing helium-detonation models for a sub-Chandrasekhar-mass white dwarf (black dashed line) and a Chandrasekhar-mass white dwarf (red line).
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Jiang, Ja., Doi, M., Maeda, K. et al. A hybrid type Ia supernova with an early flash triggered by helium-shell detonation. Nature 550, 80–83 (2017). https://doi.org/10.1038/nature23908
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