The low-luminosity Type II SN 2016aqf: a well-monitored spectral evolution of the Ni/Fe abundance ratio

Tomás E. Müller-Bravo, Claudia P. Gutiérrez, Mark Sullivan, Anders Jerkstrand, Joseph P. Anderson, Santiago González-Gaitán, Jesper Sollerman, Iair Arcavi, Jamison Burke, Lluis Galbany, Avishay Gal-Yam, Mariusz Gromadzki, Daichi Hiramatsu, Griffin Hosseinzadeh, D. Andrew Howell, Cosimo Inserra, Erki Kankare, Alexandra Kozyreva, Curtis McCully, Matt NichollStephen Smartt, Stefano Valenti, Dave R. Young

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1 Citation (Scopus)


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, an LL SN II with extensive spectral and photometric coverage. We measure a V-band peak magnitude of −14.58 mag, a plateau duration of ∼100 d, and an inferred 56Ni mass of 0.008 ± 0.002 M☉. The peak bolometric luminosity, L bol ≈ 10 41.4 erg s −1, and its spectral evolution are typical of other SNe in the class. Using our late-time spectra, we measure the [O I] λλ6300, 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 ± 3 M☉. Our extensive late-time spectral coverage of the [Fe II] λ7155 and [Ni II] λ7378 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 0 009 010 and argue that the best epochs to measure the ratio are at ∼200-300 d 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 that 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.

Original languageEnglish
Pages (from-to)361-377
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 1 Jul 2020

Bibliographical note

Publisher Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society


  • techniques: photometric
  • spectroscopic telescopes
  • supernovae: individual: SN 2016aqf
  • transients: supernovae
  • Astrophysics - High Energy Astrophysical Phenomena
  • Astrophysics - Solar and Stellar Astrophysics


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