TY - JOUR
T1 - A hybrid type Ia supernova with an early flash triggered by helium-shell detonation
AU - Jiang, Ji An
AU - Doi, Mamoru
AU - Maeda, Keiichi
AU - Shigeyama, Toshikazu
AU - Nomoto, Ken'ichi
AU - Yasuda, Naoki
AU - Jha, Saurabh W.
AU - Tanaka, Masaomi
AU - Morokuma, Tomoki
AU - Tominaga, Nozomu
AU - Ivezic, Željko
AU - Ruiz-Lapuente, Pilar
AU - Stritzinger, Maximilian D.
AU - Mazzali, Paolo A.
AU - Ashall, Christopher
AU - Mould, Jeremy
AU - Baade, Dietrich
AU - Suzuki, Nao
AU - Connolly, Andrew J.
AU - Patat, Ferdinando
AU - Wang, Lifan
AU - Yoachim, Peter
AU - Jones, David
AU - Furusawa, Hisanori
AU - Miyazaki, Satoshi
N1 - Publisher Copyright:
© 2017 Macmillan Publishers Limited, part of Springer Nature.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/10/4
Y1 - 2017/10/4
N2 - Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen1,2. The uniformity of their light curves makes these supernovae powerful cosmological distance indicators3,4, but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved2,5,6. For example, the recent detection of the early ultraviolet pulse of a peculiar, subluminous type Ia supernova has been claimed as evidence for an interaction between a red-giant or a main-sequence companion and ejecta from a whitedwarf explosion7,8. Here we report observations of a prominent but red optical flash that appears about half a day after the explosion of a type Ia supernova. This supernova shows hybrid features of different supernova subclasses, namely a light curve that is typical of normalbrightness supernovae, but with strong titanium absorption, which is commonly seen in the spectra of subluminous ones. We argue that this early flash does not occur through previously suggested mechanisms such as the companion-ejecta interaction8-10. Instead, our simulations show that it could occur through detonation of a thin helium shell either on a near-Chandrasekhar-mass white dwarf, or on a sub-Chandrasekhar-mass white dwarf merging with a lessmassive white dwarf. Our finding provides evidence that one branch of previously proposed explosion models-the helium-ignition branch-does exist in nature, and that such a model may account for the explosions of white dwarfs in a mass range wider than previously supposed11-14.
AB - Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen1,2. The uniformity of their light curves makes these supernovae powerful cosmological distance indicators3,4, but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved2,5,6. For example, the recent detection of the early ultraviolet pulse of a peculiar, subluminous type Ia supernova has been claimed as evidence for an interaction between a red-giant or a main-sequence companion and ejecta from a whitedwarf explosion7,8. Here we report observations of a prominent but red optical flash that appears about half a day after the explosion of a type Ia supernova. This supernova shows hybrid features of different supernova subclasses, namely a light curve that is typical of normalbrightness supernovae, but with strong titanium absorption, which is commonly seen in the spectra of subluminous ones. We argue that this early flash does not occur through previously suggested mechanisms such as the companion-ejecta interaction8-10. Instead, our simulations show that it could occur through detonation of a thin helium shell either on a near-Chandrasekhar-mass white dwarf, or on a sub-Chandrasekhar-mass white dwarf merging with a lessmassive white dwarf. Our finding provides evidence that one branch of previously proposed explosion models-the helium-ignition branch-does exist in nature, and that such a model may account for the explosions of white dwarfs in a mass range wider than previously supposed11-14.
UR - http://www.scopus.com/inward/record.url?scp=85030767936&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85030767936&partnerID=8YFLogxK
U2 - 10.1038/nature23908
DO - 10.1038/nature23908
M3 - Article
C2 - 28980637
AN - SCOPUS:85030767936
VL - 550
SP - 80
EP - 83
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7674
ER -