SN 2013fs and SN 2013fr: Exploring the circumstellar-material diversity in Type II supernovae

Christopher Bullivant, Nathan Smith, G. Grant Williams, Jon C. Mauerhan, Jennifer E. Andrews, Wen Fai Fong, Christopher Bilinski, Charles D. Kilpatrick, Peter A. Milne, Ori D. Fox, S. Bradley Cenko, Alexei V. Filippenko, Wei Kang Zheng, Patrick L. Kelly, Kelsey I. Clubb

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


We present photometry and spectroscopy of SN 2013fs and SN 2013fr in the first~100 d postexplosion. Both objects showed transient, relatively narrow Hα emission lines characteristic of SNe IIn, but later resembled normal SNe II-P or SNe II-L, indicative of fleeting interaction with circumstellar material (CSM). SN 2013fs was discovered within 8 h of explosion; one of the earliest SNe discovered thus far. Its light curve exhibits a plateau, with spectra revealing strong CSM interaction at early times. It is a less luminous version of the transitional SN IIn PTF11iqb, further demonstrating a continuum of CSM interaction intensity between SNe II-P and SNe IIn. It requires dense CSM within 6.5 × 1014 cm of the progenitor, from a phase of advanced pre-SN mass loss beginning shortly before explosion. Spectropolarimetry of SN 2013fs shows little continuum polarization (~0.5 per cent, consistent with zero), but noticeable line polarization during the plateau phase. SN 2013fr morphed from an SN IIn at early times to an SN II-L. After the first epoch, its narrow lines probably arose from host-galaxy emission, but the bright, narrow Hα emission at early times may be intrinsic to the SN. As for SN 2013fs, this would point to a short-lived phase of strong CSM interaction if proven to be intrinsic, suggesting a continuum between SNe IIn and SNe II-L. It is a low-velocity SN II-L like SN 2009kr, but more luminous. SN 2013fr also developed an infrared excess at later times, due to warm CSM dust that requires a more sustained phase of strong pre-SN mass loss.

Original languageEnglish (US)
Pages (from-to)1497-1518
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - May 11 2018


  • Circumstellar matter
  • Stars: mass-loss
  • Supernovae: general
  • Supernovae: individual (SN 2013fs, SN 2013fr)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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