The continuing story of SN IIb 2013df: new optical and IR observations and analysis

Tamás Szalai*, József Vinkó, Andrea P. Nagy, Jeffrey M. Silverman, J. Craig Wheeler, Govinda Dhungana, G. Howie Marion, Robert Kehoe, Ori D. Fox, Krisztián Sárneczky, Gábor Marschalkó, Barna I. Bíró, Tamás Borkovits, Tibor Hegedüs, Róbert Szakáts, Farley V. Ferrante, Evelin Bányai, Gabriella Hodosán, János Kelemen, András Pál

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


SN 2013df is a nearby Type IIb supernova that seems to be the spectroscopic twin of the well-known SN 1993J. Previous studies revealed many, but not all interesting properties of this event. Our goal was to add new understanding of both the early- and late-time phases of SN 2013df. Our spectral analysis is based on six optical spectra obtained with the 9.2 m Hobby-Eberly Telescope during the first month after explosion, complemented by a near-infrared spectrum. We applied the SYNAPPS spectral synthesis code to constrain the chemical composition and physical properties of the ejecta. A principal result is the identification of 'high-velocity' He i lines in the early spectra of SN 2013df, manifest as the blue component of the double-troughed profile at ~5650 Å. This finding, together with the lack of clear separation of H and He lines in velocity space, indicates that both H and He features form at the outer envelope during the early phases. We also obtained ground-based BVRI and g'r'i'z' photometric data up to +45 d and unfiltered measurements with the ROTSE-IIIb telescope up to +168 d. From the modelling of the early-time quasi-bolometric light curve, we find Mej ~ 3.2-4.6 M and Ekin ~ 2.6-2.8 × 1051 erg for the initial ejecta mass and the initial kinetic energy, respectively, which agree well with the values derived from the separate modelling of the light-curve tail. Late-time mid-infrared excess indicates circumstellar interaction starting ~1 yr after explosion, in accordance with previously published optical, X-ray, and radio data.

Original languageEnglish
Pages (from-to)1500-1518
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Early online date1 May 2016
Publication statusPublished - 1 Aug 2016


  • Supernovae: general
  • Supernovae: individual: SN 2013df


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