Comparison of progenitor mass estimates for the Type IIP SN 2012A

L. Tomasella, E. Cappellaro, M. Fraser, M. L. Pumo, A. Pastorello, G. Pignata, S. Benetti, F. Bufano, M. Dennefeld, A. Harutyunyan, T. Iijima, A. Jerkstrand, E. Kankare, R. Kotak, L. Magill, V. Nascimbeni, P. Ochner, A. Siviero, S. Smartt, J. SollermanV. Stanishev, F. Taddia, S. Taubenberger, M. Turatto, S. Valenti, D. E. Wright, L. Zampieri

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We present the one-year long observing campaign of SN 2012A which exploded in the nearby (9.8 Mpc) irregular galaxy NGC 3239. The photometric evolution is that of a normal Type IIP supernova, but the plateau is shorter and the luminosity not as constant as in other supernovae of this type. The absolute maximum magnitude, with MB = -16.23 ± 0.16 mag, is close to the average for SN IIP. Thanks also to the strong UV flux in the early phase, SN 2012A reached a peak luminosity of about 2 × 1042 erg s-1, which is brighter than those of other SNe with a similar 56Ni mass. The latter was estimated from the luminosity in the exponential tail of the light curve and found to be M(56Ni) = 0.011 ± 0.004M⊙, whichis intermediate between standard and faint SN IIP. The spectral evolution of SN 2012A is also typical of SN IIP, from the early spectra dominated by a blue continuum and very broad (~104 km s-1) Balmer lines, to the late-photospheric spectra characterized by prominent P-Cygni features of metal lines (Fe II, ScII, BaII, Ti II, CaII, NaI D). The photospheric velocity is moderately low, ~3 × 103 km s-1 at 50 d, for the low optical depth metal lines. The nebular spectrum obtained 394 d after the shock breakout shows the typical features of SNe IIP and the strength of the [O I] doublet suggests a progenitor of intermediate mass, similar to SN 2004et (~15M⊙). A candidate progenitor for SN 2012A has been identified in deep, pre-explosion K'-band Gemini North Near-InfraRed Imager and Spectrometerimages, and found to be consistent with a star with a bolometric magnitude -7.08 ± 0.36 (log L/L⊙ = 4.73 ± 0.14 dex). The magnitude of the recovered progenitor in archival images points towards a moderate-mass 10.5+4.5-2 M⊙ star as the precursor of SN 2012A. The explosion parameters and progenitor mass were also estimated by means of a hydrodynamical model, fitting the bolometric light curve, the velocity and the temperature evolutio. We found a best fit for a kinetic energy of 0.48 foe, an initial radius of 1.8 × 1013 cmand ejecta mass of 12.5M⊙. Even including the mass for the compact remnant, this appears fully consistent with the direct measurements given above.

Original languageEnglish (US)
Pages (from-to)1636-1657
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Sep 1 2013


  • General - supernovae: individual
  • Individual
  • NGC 3239
  • SN 2012A - galaxies
  • Supernovae


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