SN 2016dsg: A Thermonuclear Explosion Involving a Thick Helium Shell

Yize Dong, Stefano Valenti, Abigail Polin, Aoife Boyle, Andreas Flörs, Christian Vogl, Wolfgang E. Kerzendorf, David J. Sand, Saurabh W. Jha, Łukasz Wyrzykowski, K. Azalee Bostroem, Jeniveve Pearson, Curtis McCully, Jennifer E. Andrews, Stefano Benetti, Stéphane Blondin, L. Galbany, Mariusz Gromadzki, Griffin Hosseinzadeh, D. Andrew HowellCosimo Inserra, Jacob E. Jencson, Michael Lundquist, J. D. Lyman, Mark Magee, Kate Maguire, Nicolas Meza, Shubham Srivastav, Stefan Taubenberger, J. H. Terwel, Samuel Wyatt, D. R. Young

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


A thermonuclear explosion triggered by a He-shell detonation on a carbon-oxygen white-dwarf core has been predicted to have strong UV line blanketing at early times due to the iron-group elements produced during He-shell burning. We present the photometric and spectroscopic observations of SN 2016dsg, a subluminous peculiar Type I supernova consistent with a thermonuclear explosion involving a thick He shell. With a redshift of 0.04, the i-band peak absolute magnitude is derived to be around −17.5. The object is located far away from its host, an early-type galaxy, suggesting it originated from an old stellar population. The spectra collected after the peak are unusually red, show strong UV line blanketing and weak O i λ7773 absorption lines, and do not evolve significantly over 30 days. An absorption line around 9700-10500 Å is detected in the near-infrared spectrum and is likely from the unburnt He in the ejecta. The spectroscopic evolution is consistent with the thermonuclear explosion models for a sub-Chandrasekhar-mass white dwarf with a thick He shell, while the photometric evolution is not well described by existing models.

Original languageEnglish (US)
Article number102
JournalAstrophysical Journal
Issue number2
StatePublished - Aug 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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