PTF11iqb: cool supergiant mass-loss that bridges the gap between Type IIn and normal supernovae

Nathan Smith, Jon C. Mauerhan, S. Bradley Cenko, Mansi M. Kasliwal, Jeffrey M. Silverman, Alexei V. Filippenko, Avishay Gal-Yam, Kelsey I. Clubb, Melissa L. Graham, Douglas C. Leonard, J. Chuck Horst, G. Grant Williams, Jennifer E. Andrews, Shrinivas R. Kulkarni, Peter Nugent, Mark Sullivan, Kate Maguire, Dong Xu, Sagi Ben-Ami

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PTF11iqb was initially classified as a TypeIIn event caught very early after explosion. It showed narrow Wolf-Rayet (WR) spectral features on day 2, but the narrow emission weakened quickly and the spectrum morphed to resemble those of Types II-L and II-P. At late times, Halpha emission exhibited a complex, multipeaked profile reminiscent of SN1998S. In terms of spectroscopic evolution, we find that PTF11iqb was a near twin of SN~1998S, although with weaker interaction with circumstellar material (CSM) at early times, and stronger CSM interaction at late times. We interpret the spectral changes as caused by early interaction with asymmetric CSM that is quickly (by day 20) enveloped by the expanding SN ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. The light curve can be matched with a simple model for weak CSM interaction added to the light curve of a normal SN~II-P. This plateau requires that the progenitor had an extended H envelope like a red supergiant, consistent with the slow progenitor wind speed indicated by narrow emission. The cool supergiant progenitor is significant because PTF11iqb showed WR features in its early spectrum --- meaning that the presence of such WR features in an early SN spectrum does not necessarily indicate a WR-like progenitor. [abridged] Overall, PTF11iqb bridges SNe~IIn with weaker pre-SN mass loss seen in SNe II-L and II-P, implying a continuum between these types.
Original languageEnglish
Pages (from-to)1876-1896
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Early online date26 Mar 2015
Publication statusPublished - 11 May 2015


  • Astrophysics - High Energy Astrophysical Phenomena
  • Astrophysics - Solar and Stellar Astrophysics

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    Smith, N., Mauerhan, J. C., Cenko, S. B., Kasliwal, M. M., Silverman, J. M., Filippenko, A. V., Gal-Yam, A., Clubb, K. I., Graham, M. L., Leonard, D. C., Horst, J. C., Williams, G. G., Andrews, J. E., Kulkarni, S. R., Nugent, P., Sullivan, M., Maguire, K., Xu, D., & Ben-Ami, S. (2015). PTF11iqb: cool supergiant mass-loss that bridges the gap between Type IIn and normal supernovae. Monthly Notices of the Royal Astronomical Society, 449(2), 1876-1896.