Back to Search Start Over

A hybrid type Ia supernova with an early flash triggered by helium-shell detonation

Authors :
Jiang, Ji-an
Doi, Mamoru
Maeda, Keiichi
Shigeyama, Toshikazu
Nomoto, Ken'ichi
Yasuda, Naoki
Jha, Saurabh W.
Tanaka, Masaomi
Morokuma, Tomoki
Tominaga, Nozomu
Ivezić, Željko
Ruiz-Lapuente, Pilar
Stritzinger, Maximilian D.
Mazzali, Paolo A.
Ashall, Christopher
Mould, Jeremy
Baade, Dietrich
Suzuki, Nao
Connolly, Andrew J.
Patat, Ferdinando
Wang, Lifan
Yoachim, Peter
Jones, David
Furusawa, Hisanori
Miyazaki, Satoshi
Publication Year :
2017

Abstract

Type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of carbon-oxygen white dwarfs. Though the uniformity of their light curves makes them powerful cosmological distance indicators, long-standing issues remain regarding their progenitors and explosion mechanisms. Recent detection of the early ultraviolet pulse of a peculiar subluminous SN Ia has been claimed as new evidence for the companion-ejecta interaction through the single-degenerate channel. Here, we report the discovery of a prominent but red optical flash at $\sim$ 0.5 days after the explosion of a SN Ia which shows hybrid features of different SN Ia sub-classes: a light curve typical of normal-brightness SNe Ia, but with strong titanium absorptions, commonly seen in the spectra of subluminous ones. We argue that the early flash of such a hybrid SN Ia is different from predictions of previously suggested scenarios such as the companion-ejecta interaction. Instead it can be naturally explained by a SN explosion triggered by a detonation of a thin helium shell either on a near-Chandrasekhar-mass white dwarf ($\gtrsim$ 1.3 M$_{\odot}$) with low-yield $^{56}$Ni or on a sub-Chandrasekhar-mass white dwarf ($\sim$ 1.0 M$_{\odot}$) merging with a less massive white dwarf. This finding provides compelling evidence that one branch of the previously proposed explosion models, the helium-ignition scenario, does exist in nature, and such a scenario may account for explosions of white dwarfs in a wider mass range in contrast to what was previously supposed.<br />Comment: Accepted for publication in Nature on August 9, 2017 (the original version was submitted on May 3, 2017)

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.1710.01824
Document Type :
Working Paper
Full Text :
https://doi.org/10.1038/nature23908