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

分类： 天文学 >> 天文学 提交时间： 2023-02-19

Yize Dong Stefano Valenti Abigail Polin Aoife Boyle andreas flörs Christian Vogl Wolfgang Kerzendorf David Sand Saurabh Jha Lukasz Wyrzykowski K. Bostroem Jeniveve Pearson Curtis McCully Jennifer Andrew Stefano Benettii Stephane Blondin Lluís Galbany Mariusz Gromadzki Griffin Hosseinzadeh D. Andrew Howell

摘要： A thermonuclear explosion triggered by a helium-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 helium-shell burning. We present the photometric and spectroscopic observations of SN 2016dsg, a sub-luminous peculiar Type I SN 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 $\lambda$7773 absorption lines, and do not evolve significantly over 30 days. An absorption line around 9700-10500 \AA is detected in the near-infrared spectrum and is likely from the unburnt helium in the ejecta. The spectroscopic evolution is consistent with the thermonuclear explosion models for a sub-Chandrasekhar mass white dwarf with a thick helium shell, while the photometric evolution is not well described by existing models.

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