Ca hnk the calcium-rich transient supernova 2016hnk from a helium shell detonation of a sub-Chandrasekhar white dwarf. (2020)
Keywords :
Type Ia supernovae ; White dwarf stars ; Supernovae ; Observational astronomy
Abstract:We present observations and modeling of SN 2016hnk, a Ca-rich supernova (SN) that is consistent with being the result of a He-shell double-detonation explosion of a C/O white dwarf. We find that SN2016hnk is intrinsically red relative to typical thermonuclear SNe and has a relatively low peak luminosity (M_B_=-15.4mag), setting it apart from low-luminosity SNe Ia. SN 2016hnk has a fast-rising light curve that is consistent with other Ca-rich transients (t_r_=15days). We determine that SN 2016hnk produced 0.03+/-0.01M_{sun}_ of ^56^Ni and 0.9+/-0.3M_{sun}_ of ejecta. The photospheric spectra show strong, high-velocity CaII absorption and significant line blanketing at {lambda}<5000{AA}, making it distinct from typical (SN 2005E-like)
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SN 2016hnk was discovered by the Asteroid Terrestrial-impact Last
Alert System (ATLAS) on 2016 October 27 (MJD 57688) using the ACAM1
instrument with a cyan filter.
We imaged SN 2016hnk between 2016 November 1 and 2017 February 17 with
the Direct camera on the Swope 1m telescope at Las Campanas
Observatory, Chile. Observations were performed in Johnson BV and
Sloan ugri filters.
Additional imaging of SN 2016hnk was obtained by the Las Cumbres
Observatory Global Telescope (LCOGT) and the Foundation Supernova
Survey with Pan-STARRS.
Final photometric observations of SN 2016hnk were obtained using the
imaging camera on the Keck telescope Low-resolution Imaging
Spectrometer (LRIS). The source was observed on 2017 July 20 in BR as
well as on 2017 August 16 in BVRI.
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