The peculiar type II supernova 1997D: A case for a very low56Ni mass

M. Turatto, P. A. Mazzali, T. R. Young, K. Nomoto, K. Iwamoto, S. Benetti, E. Cappellaro, I. J. Danziger, D. F. De Mello, M. M. Phillips, N. B. Suntzeff, A. Clocchiatti, A. Piemonte, B. Leibundgut, R. Covarrubias, J. Maza, J. Sollerman

Research output: Contribution to journalArticlepeer-review


SN 1997D in NGC 1536 is possibly the least luminous and energetic Type II supernova discovered to date. The entire light curve is subluminous, never reaching Mv = -14.65. The radioactive tail follows the 56Co decay slope. In the case of a nearly complete trapping of the γ-rays, the 36Ni mass derived from the tail brightness is extremely small, ∼0.002 M. At discovery, the spectra showed a red continuum and line velocities on the order of 1000 km s-1. The luminosity and the photospheric expansion velocity suggest that the explosion occurred about 50 days before discovery and that a plateau probably followed. Model light curves and spectra of the explosion of a 26 M̈ star successfully fitted the observations. Low-mass models are inconsistent with the observations. The radius of the progenitor, constrained by the prediscovery upper limits, is R0 ≳ 300 R. A low explosion energy of ∼4 × 1050 ergs is then required in the modeling. The strong Ba n lines in the photospheric spectra are reproduced with a solar abundance and low Teff. A scenario in which the low 56Ni mass observed in SN 1997D is due to fallback of material onto the collapsed remnant of the explosion of a 25-40 M star appears to be favored over the case of the explosion of an 8-10 M star with low 56Ni production.

Original languageEnglish (US)
Pages (from-to)L129-L133
JournalAstrophysical Journal
Issue number2 PART II
StatePublished - 1998
Externally publishedYes


  • Nuclear reactions, nucleosynthesis, abundances
  • Stars: evolution
  • Supernovae: general
  • Supernovae: individual (SN 1997D)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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