The nebular spectra of SN 2012aw and constraints on stellar nucleosynthesis from oxygen emission lines

• We present nebular-phase optical and near-infrared spectroscopy of the Type IIP supernova SN 2012aw combined with non-local thermodynamic equilibrium radiative transfer calculations applied to ejecta from stellar evolution/explosion models. Our spectral synthesis models generally show good agreement with the ejecta from a M-ZAMS = 15 M-circle dot progenitor star. The emission lines of oxygen, sodium, and magnesium are all consistent with the nucleosynthesis in a progenitor in the 14-18 M-circle dot range. We also demonstrate how the evolution of the oxygen cooling lines of [O i] lambda 5577, [O i] lambda 6300, and [O i] lambda 6364 can be used to constrain the mass of oxygen in the non-molecularly cooled ashes to < 1 M-circle dot, independent of the mixing in the ejecta. This constraint implies that any progenitor model of initial mass greater than 20 M-circle dot would be difficult to reconcile with the observed line strengths. A stellar progenitor of around M-ZAMS = 15 M-circle dot can consistently explain the directly measured luminosity of the progenitor star, the observed nebular spectra, and the inferred pre-supernova mass-loss rate. We conclude that there is still no convincing example of a Type IIP supernova showing the nucleosynthesis products expected from an M-ZAMS > 20 M-circle dot progenitor.

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

radiative transfer

stars: evolution

supernovae: general

supernovae: individual: SN 2012aw

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)