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

Journal article

Abstract 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 λ 7773 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.

Authors: Dong, Y; Valenti, S; Polin, A; Boyle, A; Flörs, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 934
• Issue: 2
• Pages: 102-102
• Publication date: 2022-07-28
• DOI: 10.3847/1538-4357/ac75eb
• EISSN: 1538-4357
• ISSN: 0004-637X
• Language: English
• Keywords: Astronomy; Blanketing; Supergiant; Astrophysics; Plasma; Redshift; Red supergiant; White dwarf; Supernova; Nuclear physics; Physics; Thermonuclear fusion; Red giant; Stars; Galaxy