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 _ { \odot } progenitor star ( with an oxygen mass of 0.8 M _ { \odot } ) to satisfactorily reproduce [ O i ] \lambda \lambda 6300 , 6364 and other emission lines of carbon , sodium , magnesium , and silicon , while 12 M _ { \odot } and 19 M _ { \odot } 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 ) \simeq 7 \times 10 ^ { -14 } \times ( \mbox { t } / 100 ~ { } \mbox { 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 .