Low-luminosity type II supernovae ( LL SNe II ) make up the low explosion energy end of core-collapse SNe , but their study and physical understanding remain limited .
We present SN 2016aqf , a LL SN II with extensive spectral and photometric coverage .
We measure a V -band peak magnitude of -14.58 mag , a plateau duration of \sim 100 days , and an inferred ^ { 56 } Ni mass of 0.008 \pm 0.002 M _ { \sun } .
The peak bolometric luminosity , L _ { bol } \approx 10 ^ { 41.4 } erg s ^ { -1 } , and its spectral evolution is typical of other SNe in the class .
Using our late-time spectra , we measure the [ \ion Oi ] \lambda \lambda 6300 , 6364 lines , which we compare against SN II spectral synthesis models to constrain the progenitor zero-age main-sequence mass .
We find this to be 12 \pm 3 M _ { \sun } .
Our extensive late-time spectral coverage of the [ \ion Feii ] \lambda 7155 and [ \ion Niii ] \lambda 7378 lines permits a measurement of the Ni/Fe abundance ratio , a parameter sensitive to the inner progenitor structure and explosion mechanism dynamics .
We measure a constant abundance ratio evolution of 0.081 ^ { +0.009 } _ { -0.010 } , and argue that the best epochs to measure the ratio are at \sim 200 – 300 days after explosion .
We place this measurement in the context of a large sample of SNe II and compare against various physical , light-curve and spectral parameters , in search of trends which might allow indirect ways of constraining this ratio .
We do not find correlations predicted by theoretical models ; however , this may be the result of the exact choice of parameters and explosion mechanism in the models , the simplicity of them and/or primordial contamination in the measured abundance ratio .