The progenitor mass of the Type IIP supernova SN 2004et from late-time spectral modeling

SN 2004et is one of the nearest and best-observed Type IIP supernovae, with a progenitor detection as well as good photometric and spectroscopic observational coverage well into the nebular phase. Based on nucleosynthesis from stellar evolution/explosion models we apply spectral modeling to analyze its 140-700 day evolution from ultraviolet to mid-infrared. We find a M-ZAMS = 15 M-circle dot progenitor star (with an oxygen mass of 0.8 M-circle dot) to satisfactorily reproduce [Oi] lambda lambda 6300, 6364 and other emission lines of carbon, sodium, magnesium, and silicon, while 12 M-circle dot and 19 M-circle dot models under-and overproduce most of these lines, respectively. This result is in fair agreement with the mass derived from the progenitor detection, but in disagreement with hydrodynamical modeling of the early-time light curve. From modeling of the mid-infrared iron-group emission lines, we determine the density of the "Ni-bubble" to rho(t) similar or equal to 7 x 10(-14) x (t/100 d)(-3) g cm(-3), corresponding to a filling factor of f = 0.15 in the metal core region (V = 1800 km s(-1)). We also confirm that silicate dust, CO, and SiO emission are all present in the spectra.