OGLE-2013-SN-079: a lonely supernova consistent with a helium shell detonation

Abstract

We present observational data for a peculiar supernova discovered by the OGLE-IV survey and followed by the Public ESO Spectroscopic Survey for Transient Objects. The inferred redshift of $z=0.07$ implies an absolute magnitude in the rest-frame $I$-band of M${}_I\sim -17.6$ mag. This places it in the luminosity range between normal Type Ia SNe and novae. Optical and near infrared spectroscopy reveal mostly Ti and Ca lines, and an unusually red color arising from strong depression of flux at rest wavelengths $<5000$ Å. To date, this is the only reported SN showing Ti-dominated spectra. The data are broadly consistent with existing models for the pure detonation of a helium shell around a low-mass CO white dwarf and "double-detonation" models that include a secondary detonation of a CO core following a primary detonation in an overlying helium shell.

ApJ Letter accepted on the 5th of December 2014. 8 pages, 3 figures. This version matches the upcoming published one

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Cited by in corpus (6)

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• Two New Calcium-Rich Gap Transients in Group and Cluster Environments
• Nucleosynthesis imprints from different Type Ia Supernova explosion scenarios and implications for galactic chemical evolution
• One-dimensional non-LTE time-dependent radiative transfer of an He-detonation model and the connection to faint and fast-decaying supernovae
• Helium in Double-Detonation Models of Type Ia Supernovae
• Turbulent Mixing on Helium-Accreting White Dwarfs