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A year-long plateau in the late-time near-infrared light curves of type Ia supernovae


The light curves of type Ia supernovae are routinely used to constrain cosmology models. Driven by radioactive decay of 56Ni, the light curves steadily decline over time, but after 150 d post-explosion the near-infrared portion is poorly characterized. We report a year-long plateau in the near-infrared light curve at 150–500 d, followed by a second decline phase accompanied by a possible appearance of [Fe i] emission lines. This near-infrared plateau contrasts sharply with type IIP plateaux and requires a new physical mechanism. We suggest a masking of the ‘near-infrared catastrophe’—a predicted, yet unobserved, sharp light-curve decline—by scattering of ultraviolet photons to longer wavelengths. The transition off the plateau could be due to a change in the dominant ionization state of the supernova ejecta. Our results help explain the complex radiative transfer processes that take place in type Ia supernovae and enhance their use as ‘standard candles’.

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Fig. 1: HST colour composites.
Fig. 2: SN Ia NIR light curves.
Fig. 3: Correlations between NIR light-curve properties.
Fig. 4: Fraction of NIR light out of the combined optical (F350LP) and NIR (F160W) flux.
Fig. 5: HST grism spectrum of SN 2017erp at 605 d, compared with ground-based spectra of the SN at 289, 347, and 373 d.
Fig. 6: A theoretical explanation for the NIR plateau.

Data availability

HST observations are available through MAST. Supplementary Tables 1 and 2 and the data for Figs. 2–5 (Supplementary Data 1, 2, 3 and 4) are provided as machine-readable tables. Any further data are available from the corresponding author on reasonable request.


  1. 1.

    Truran, J. W., Arnett, W. D. & Cameron, A. G. W. Nucleosynthesis in supernova shock waves. Can. J. Phys. 45, 2315–231 (1967).

    ADS  Google Scholar 

  2. 2.

    Colgate, S. A. & McKee, C. Early supernova luminosity. Astrophys. J. 157, 623–62 (1969).

    ADS  Google Scholar 

  3. 3.

    Arnett, W. D. Type I supernovae. I—Analytic solutions for the early part of the light curve. Astrophys. J. 253, 785–797 (1982).

    ADS  Google Scholar 

  4. 4.

    Axelrod, T. S. Late Time Optical Spectra from the Ni-56 Model for Type 1 Supernovae. PhD thesis, Univ. California, Santa Cruz (1980).

  5. 5.

    Cappellaro, E. et al. SN IA light curves and radioactive decay. Astron. Astrophys. 328, 203–210 (1997).

    ADS  Google Scholar 

  6. 6.

    Leloudas, G. et al. The normal Type Ia SN 2003hv out to very late phases. Astron. Astrophys. 505, 265–279 (2009).

    ADS  Google Scholar 

  7. 7.

    Fransson, C. & Jerkstrand, A. Reconciling the infrared catastrophe and observations of SN 2011fe. Astrophys. J. 814, L2 (2015).

    ADS  Google Scholar 

  8. 8.

    Graur, O. et al. Late-time photometry of Type Ia supernova SN 2012cg reveals the radioactive decay of 57Co. Astrophys. J. 819, 31 (2016).

    ADS  Google Scholar 

  9. 9.

    Graur, O. et al. Observations of SN 2015F suggest a correlation between the intrinsic luminosity of Type Ia supernovae and the shape of their light curves >900 days after explosion. Astrophys. J. 859, 79 (2018).

    ADS  Google Scholar 

  10. 10.

    Graur, O. et al. Late-time observations of ASASSN-14lp strengthen the case for a correlation between the peak luminosity of Type Ia supernovae and the shape of their late-time light curves. Astrophys. J. 866, 10 (2018).

    ADS  Google Scholar 

  11. 11.

    Graur, O. Late-time observations of the Type Ia supernova SN 2014J with the Hubble Space Telescope Wide Field Camera 3. Astrophys. J. 870, 14 (2019).

    ADS  Google Scholar 

  12. 12.

    Shappee, B. J., Stanek, K. Z., Kochanek, C. S. & Garnavich, P. M. Whimper of a bang: documenting the final days of the nearby Type Ia supernova 2011fe. Astrophys. J. 841, 48 (2017).

    ADS  Google Scholar 

  13. 13.

    Yang, Y. et al. Late-time flattening of Type Ia supernova light curves: constraints from SN 2014J in M82. Astrophys. J. 852, 89 (2018).

    ADS  Google Scholar 

  14. 14.

    Dimitriadis, G. et al. The late-time light curve of the Type Ia supernova SN 2011fe. Mon. Not. R. Astron. Soc. 468, 3798–3812 (2017).

    ADS  Google Scholar 

  15. 15.

    Kerzendorf, W. E. et al. Extremely late photometry of the nearby SN 2011fe. Mon. Not. R. Astron. Soc. 472, 2534–2542 (2017).

    ADS  Google Scholar 

  16. 16.

    Li, W. et al. Observations of Type Ia supernova 2014J for nearly 900 days and constraints on its progenitor system. Astrophys. J. 882, 30 (2019).

    ADS  Google Scholar 

  17. 17.

    Chevalier, R. A. The hydrodynamics of Type II supernovae. Astrophys. J. 207, 872–887 (1976).

    ADS  Google Scholar 

  18. 18.

    Candia, P. et al. Optical and infrared photometry of the unusual Type Ia supernova 2000cx. Publ. Astron. Soc. Pac. 115, 277–294 (2003).

    ADS  Google Scholar 

  19. 19.

    Krisciunas, K. et al. Optical and infrared photometry of the nearby Type Ia supernova 2001el. Astron. J. 125, 166–180 (2003).

    ADS  Google Scholar 

  20. 20.

    Sollerman, J. et al. The late-time light curve of the Type Ia supernova 2000cx. Astron. Astrophys. 428, 555–568 (2004).

    ADS  Google Scholar 

  21. 21.

    Stritzinger, M. & Sollerman, J. Late-time emission of Type Ia supernovae: optical and near-infrared observations of SN 2001el. Astron. Astrophys. 470, L1–L4 (2007).

    ADS  Google Scholar 

  22. 22.

    Pastorello, A. et al. ESC and KAIT observations of the transitional Type Ia SN 2004eo. Mon. Not. R. Astron. Soc. 377, 1531–1552 (2007).

    ADS  Google Scholar 

  23. 23.

    Matheson, T. et al. The infrared light curve of SN 2011fe in M101 and the distance to M101. Astrophys. J. 754, 19 (2012).

    ADS  Google Scholar 

  24. 24.

    Pan, Y.-C. et al. 500 days of SN 2013dy: spectra and photometry from the ultraviolet to the infrared. Mon. Not. R. Astron. Soc. 452, 4307–4325 (2015).

    ADS  Google Scholar 

  25. 25.

    Marion, G. H. et al. SN2012cg: evidence for interaction between a normal Type Ia supernova and a non-degenerate binary companion. Astrophys. J. 820, 92 (2016).

    ADS  Google Scholar 

  26. 26.

    Sand, D. J. et al. Post-maximum near-infrared spectra of SN 2014J: a search for interaction signatures. Astrophys. J. 822, L16 (2016).

    ADS  Google Scholar 

  27. 27.

    Burns, C. R. et al. The Carnegie Supernova Project: absolute calibration and the Hubble constant. Astrophys. J. 869, 56 (2018).

    ADS  Google Scholar 

  28. 28.

    Diamond, T. R. et al. Near-infrared spectral evolution of the Type Ia supernova 2014J in the nebular phase: implications for the progenitor system. Astrophys. J. 861, 119 (2018).

    ADS  Google Scholar 

  29. 29.

    Dhawan, S. et al. Nebular spectroscopy of SN 2014J: detection of stable nickel in near-infrared spectra. Astron. Astrophys. 619, A102 (2018).

    Google Scholar 

  30. 30.

    Spyromilio, J. et al. Optical and near infrared observations of SN 1998bu. Astron. Astrophys. 426, 547–553 (2004).

    ADS  Google Scholar 

  31. 31.

    Avelino, A. et al. Type Ia supernovae are excellent standard candles in the near-infrared. Preprint at (2019).

  32. 32.

    Li, W. et al. The unique Type Ia supernova 2000cx in NGC 524. Publ. Astron. Soc. Pac. 113, 1178–1204 (2001).

    ADS  Google Scholar 

  33. 33.

    Maguire, K. et al. Using late-time optical and near-infrared spectra to constrain Type Ia supernova explosion properties. Mon. Not. R. Astron. Soc. 477, 3567–3582 (2018).

    ADS  Google Scholar 

  34. 34.

    Graham, M. L. et al. Constraining the progenitor companion of the nearby Type Ia SN 2011fe with a nebular spectrum at +981 d. Mon. Not. R. Astron. Soc. 454, 1948–1957 (2015).

    ADS  Google Scholar 

  35. 35.

    Taubenberger, S. et al. Spectroscopy of the Type Ia supernova 2011fe past 1000 d. Mon. Not. R. Astron. Soc. 448, L48–L52 (2015).

    ADS  Google Scholar 

  36. 36.

    Patat, F. Reflections on reflexions—I. Light echoes in Type Ia supernovae. Mon. Not. R. Astron. Soc. 357, 1161–1177 (2005).

    ADS  Google Scholar 

  37. 37.

    Patat, F., Benetti, S., Cappellaro, E. & Turatto, M. Reflections on reflexions—II. Effects of light echoes on the luminosity and spectra of Type Ia supernovae. Mon. Not. R. Astron. Soc. 369, 1949–1960 (2006).

    ADS  Google Scholar 

  38. 38.

    Rest, A., Sinnott, B. & Welch, D. L. Light echoes of transients and variables in the local universe. Publ. Astron. Soc. Aust. 29, 466–481 (2012).

    ADS  Google Scholar 

  39. 39.

    Cappellaro, E. et al. Detection of a light echo from SN 1998BU. Astrophys. J. 549, L215–L218 (2001).

    ADS  Google Scholar 

  40. 40.

    Borkowski, K. J. et al. Dust destruction in Type Ia supernova remnants in the Large Magellanic Cloud. Astrophys. J. 642, L141–L144 (2006).

    ADS  Google Scholar 

  41. 41.

    Gomez, H. L. et al. Dust in historical galactic Type Ia supernova remnants with Herschel. Mon. Not. R. Astron. Soc. 420, 3557–3573 (2012).

    ADS  Google Scholar 

  42. 42.

    Nozawa, T. et al. Formation of dust in the ejecta of Type Ia supernovae. Astrophys. J. 736, 45 (2011).

    ADS  Google Scholar 

  43. 43.

    Douvion, T., Lagage, P. O., Cesarsky, C. J. & Dwek, E. Dust in the Tycho, Kepler and Crab supernova remnants. Astron. Astrophys. 373, 281–291 (2001).

    ADS  Google Scholar 

  44. 44.

    Williams, B. J. et al. Dust in a Type Ia supernova progenitor: Spitzer spectroscopy of Kepler’s supernova remnant. Astrophys. J. 755, 3 (2012).

    ADS  Google Scholar 

  45. 45.

    Mattila, S. et al. Massive stars exploding in a He-rich circumstellar medium—III. SN 2006jc: infrared echoes from new and old dust in the progenitor CSM. Mon. Not. R. Astron. Soc. 389, 141–155 (2008).

    ADS  Google Scholar 

  46. 46.

    Anupama, G. C. et al. Optical photometry and spectroscopy of the Type Ibn supernova SN 2006jc until the onset of dust formation. Mon. Not. R. Astron. Soc. 392, 894–903 (2009).

    ADS  Google Scholar 

  47. 47.

    Kasen, D. Secondary maximum in the near-infrared light curves of Type Ia supernovae. Astrophys. J. 649, 939–953 (2006).

    ADS  Google Scholar 

  48. 48.

    Höflich, P. Analysis of the Type IA supernova SN 1994D. Astrophys. J. 443, 89 (1995).

    ADS  Google Scholar 

  49. 49.

    Pinto, P. A. & Eastman, R. G. The physics of Type IA supernova light curves. II. Opacity and diffusion. Astrophys. J. 530, 757–776 (2000).

    ADS  Google Scholar 

  50. 50.

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

    ADS  Google Scholar 

  51. 51.

    Hack, W. J. et al. AstroDrizzle: more than a new MultiDrizzle. In American Astronomical Society Meeting Abstracts Vol. 220 135.15 (AAS, 2012).

  52. 52.

    Dolphin, A. E. WFPC2 stellar photometry with HSTPHOT. Publ. Astron. Soc. Pac. 112, 1383–1396 (2000).

    ADS  Google Scholar 

  53. 53.

    Deustua, S. E. et al. UVIS 2.0 Chip-Dependent Inverse Sensitivity Values Instrument Science Report WFC3 2016-03 (STScI, 2016).

  54. 54.

    Vernet, J. et al. X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope. Astron. Astrophys. 536, A105 (2011).

    Google Scholar 

  55. 55.

    Modigliani, A. et al. The X-shooter pipeline. Proc. SPIE 7737, 773728 (2010).

    Google Scholar 

  56. 56.

    Freudling, W. et al. Automated data reduction workflows for astronomy. The ESO reflex environment. Astron. Astrophys. 559, A96 (2013).

    Google Scholar 

  57. 57.

    Maguire, K., Taubenberger, S., Sullivan, M. & Mazzali, P. A. Searching for swept-up hydrogen and helium in the late-time spectra of 11 nearby Type Ia supernovae. Mon. Not. R. Astron. Soc. 457, 3254–3265 (2016).

    ADS  Google Scholar 

  58. 58.

    Kausch, W. et al. Molecfit: a general tool for telluric absorption correction. II. Quantitative evaluation on ESO-VLT/X-Shooter spectra. Astron. Astrophys. 576, A78 (2015).

    Google Scholar 

  59. 59.

    Smette, A. et al. Molecfit: a general tool for telluric absorption correction. I. Method and application to ESO instruments. Astron. Astrophys. 576, A77 (2015).

    Google Scholar 

  60. 60.

    Brown, T. M. et al. Las Cumbres Observatory Global Telescope Network. Publ. Astron. Soc. Pac. 125, 1031 (2013).

    ADS  Google Scholar 

  61. 61.

    Valenti, S. et al. The diversity of Type II supernova versus the similarity in their progenitors. Mon. Not. R. Astron. Soc. 459, 3939–3962 (2016).

    ADS  Google Scholar 

  62. 62.

    Ryan, R. E. Jr, Casertano, S. & Pirzkal, N. Linear: a novel algorithm for reconstructing slitless spectroscopy from HST/WFC3. Publ. Astron. Soc. Pac. 130, 034501 (2018).

    ADS  Google Scholar 

  63. 63.

    Troja, E. et al. The X-ray counterpart to the gravitational-wave event GW170817. Nature 551, 71–74 (2017).

    ADS  Google Scholar 

  64. 64.

    Hillier, D. J. & Miller, D. L. The treatment of non-LTE line blanketing in spherically expanding outflows. Astrophys. J. 496, 407–427 (1998).

    ADS  Google Scholar 

  65. 65.

    Hillier, D. J. & Dessart, L. Time-dependent radiative transfer calculations for supernovae. Mon. Not. R. Astron. Soc. 424, 252–271 (2012).

    ADS  Google Scholar 

  66. 66.

    Tyndall, N. B., Ramsbottom, C. A., Ballance, C. P. & Hibbert, A. Photoionization of Co+ and electron-impact excitation of Co2+ using the Dirac R-matrix method. Mon. Not. R. Astron. Soc. 462, 3350–3360 (2016).

    ADS  Google Scholar 

  67. 67.

    Quinet, P., Le Dourneuf, M. & Zeippen, C. J. Atomic data from the IRON Project. XIX. Radiative transition probabilities for forbidden lines in Fe II. Astron. Astrophys. Suppl. 120, 361–371 (1996).

    ADS  Google Scholar 

  68. 68.

    Quinet, P. Transition probabilities for forbidden lines of Fe III. Astron. Astrophys. Suppl. 116, 573–578 (1996).

    ADS  Google Scholar 

  69. 69.

    Skrutskie, M. F. et al. The Two Micron All Sky Survey (2MASS). Astron. J. 131, 1163–1183 (2006).

    ADS  Google Scholar 

  70. 70.

    Mayya, Y. D., Puerari, I. & Kuhn, O. Supernova 1998bu in NGC 3368. IAU Circ. 6907, 2 (1998).

    ADS  Google Scholar 

  71. 71.

    Jha, S. et al. The Type Ia supernova 1998bu in M96 and the Hubble constant. Astrophys. J. Suppl. Ser. 125, 73–97 (1999).

    ADS  Google Scholar 

  72. 72.

    Hernandez, M. et al. An early-time infrared and optical study of the Type Ia supernova 1998bu in M96. Mon. Not. R. Astron. Soc. 319, 223–234 (2000).

    ADS  Google Scholar 

  73. 73.

    Meikle, W. P. S. The absolute infrared magnitudes of Type Ia supernovae. Mon. Not. R. Astron. Soc. 314, 782–792 (2000).

    ADS  Google Scholar 

  74. 74.

    Brown, P. J. et al. Red and reddened: ultraviolet through near-infrared observations of Type Ia supernova 2017erp. Astrophys. J. 877, 152 (2019).

    ADS  Google Scholar 

  75. 75.

    Tully, R. B., Courtois, H. M. & Sorce, J. G. Cosmicflows-3. Astron. J. 152, 50 (2016).

    ADS  Google Scholar 

  76. 76.

    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 

  77. 77.

    Yang, Y. et al. The young and nearby normal Type Ia supernova 2018gv: UV-optical observations and the earliest spectropolarimetry. Preprint at (2019).

  78. 78.

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

    ADS  Google Scholar 

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We thank G. Brammer, D. Eisenstein, W. Kerzendorf, S. Sim and L. Strolger for helpful discussions and comments, S. Dhawan for sharing his spectra of SN 2014J and A. Calamida, W. Eck, M. Gennaro and W. Januszewski for supporting the HST programs used here. O.G. is supported by an NSF Astronomy and Astrophysics Fellowship under award AST-1602595. K.M. acknowledges support from H2020 through an ERC Starting Grant (758638). M.N. is supported by a Royal Astronomical Society Research Fellowship. R.F. acknowledges support from NASA ATP award 80NSSC18K1013. This work is based on data obtained with the NASA/ESA HST, all of which was obtained from the Mikulski Archive for Space Telescopes (MAST). Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This work is based on data taken at the European Organization for Astronomical Research in the Southern Hemisphere, Chile, under programme IDs 0100.D-0242(A) and 0101.D-0443(A). The research has made use of NASA’s Astrophysics Data System and the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The NIST databases were funded, in part, by NIST’s Standard Reference Data Program (SRDP) and by NIST’s Systems Integration for Manufacturing Applications (SIMA) Program. Finally, this work has made use of the Open Supernova Catalog78.

Author information




O.G. planned the observations for HST programs GO–15686 and 15693, reduced the HST imaging data, performed the analysis and wrote the manuscript. K.M. obtained the ground-based spectra of SN 2017erp. M.N. reduced the Gemini spectra of SN 2014J. R.R. reduced the grism observation of SN 2017erp obtained through HST program GO–15686. A.A. measured Δm100(H) values for the correlation study. A.G.R. planned the HST observations for programs GO–12880, 15145 and 15640. I.R.S., R.F. and L.S. assisted with the theoretical analysis of the observations.

Corresponding author

Correspondence to O. Graur.

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The authors declare no competing interests.

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Peer review information Nature Astronomy thanks Yi Yang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Captions for Supplementary Tables 1 and 2 and Supplementary Data 1–5.

Supplementary Table 1

Machine-readable table presenting HST photometry of SNe 2012ht, 2013dy, 2017erp, 2018gv and 2019np.

Supplementary Table 2

Machine-readable table presenting synthetic photometry of SN 2014J.

Supplementary Data 1

Source data for Fig. 2.

Supplementary Data 2

Source data for Fig. 3a.

Supplementary Data 3

Source data for Fig. 3b.

Supplementary Data 4

Source data for Fig. 4.

Supplementary Data 5

Source data for Fig. 5: machine-readable table presenting the HST grism spectrum of SN 2017erp.

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Graur, O., Maguire, K., Ryan, R. et al. A year-long plateau in the late-time near-infrared light curves of type Ia supernovae. Nat Astron 4, 188–195 (2020).

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