SN 2012au: A golden link between superluminous supernovae and their lower-luminosity counterparts

Dan Milisavljevic, Alicia M. Soderberg, Raffaella Margutti, Maria R. Drout, G. Howie Marion, Nathan E. Sanders, Eric Y. Hsiao, Ragnhild Lunnan, Ryan Chornock, Robert A. Fesen, Jerod T. Parrent, Emily M. Levesque, Edo Berger, Ryan J. Foley, Pete Challis, Robert P. Kirshner, Jason Dittmann, Allyson Bieryla, Atish Kamble, Sayan ChakrabortiGisella De Rosa, Michael Fausnaugh, Kevin N. Hainline, Chien Ting Chen, Ryan C. Hickox, Nidia Morrell, Mark M. Phillips, Maximilian Stritzinger

Research output: Contribution to journalArticlepeer-review


We present optical and near-infrared observations of SN 2012au, a slow-evolving supernova (SN) with properties that suggest a link between subsets of energetic and H-poor SNe and superluminous SNe. SN 2012au exhibited conspicuous Type-Ib-like He I lines and other absorption features at velocities reaching ≈2 × 104 km s-1 in its early spectra, and a broad light curve that peaked at MB = -18.1 mag. Models of these data indicate a large explosion kinetic energy of ∼1052 erg and 56Ni mass ejection of M Ni ≈ 0.3 M on par with SN 1998bw. SN 2012au's spectra almost one year after explosion show a blend of persistent Fe II P-Cyg absorptions and nebular emissions originating from two distinct velocity regions. These late-time emissions include strong [Fe II], [Ca II], [O I], Mg I], and Na I lines at velocities ≳ 4500 km s-1, as well as O I and Mg I lines at noticeably smaller velocities ≲ 2000 km s-1. Many of the late-time properties of SN 2012au are similar to the slow-evolving hypernovae SN 1997dq and SN 1997ef, and the superluminous SN 2007bi. Our observations suggest that a single explosion mechanism may unify all of these events that span -21 ≲ MB ≲ -17 mag. The aspherical and possibly jetted explosion was most likely initiated by the core collapse of a massive progenitor star and created substantial high-density, low-velocity Ni-rich material.

Original languageEnglish (US)
Article numberL38
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Jun 20 2013
Externally publishedYes


  • supernovae: general
  • supernovae: individual (SN 2012au)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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