Статья

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

Ji-an JiangDepartment of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, JapanMamoru DoiInstitute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, JapanKeiichi MaedaDepartment of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, JapanToshikazu ShigeyamaResearch Center for the Early Universe, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, JapanKen’ichi NomotoKavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, JapanNaoki YasudaKavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, JapanSaurabh W. JhaDepartment of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USAMasaomi TanakaKavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, JapanTomoki MorokumaInstitute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, JapanNozomu TominagaDepartment of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501, JapanŽeljko IvezićDepartment of Astronomy, University of Washington, Box 351580, Seattle, Washington 98195-1580, USAP. Ruiz‐LapuenteInstitut de Ciències del Cosmos (UB-IEEC), Calle de Martí i Franqués 1, E-08028 Barcelona, SpainM. StritzingerDepartment of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, DenmarkP. A. MazzaliAstrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UKC. AshallAstrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UKJ. R. MouldCentre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, AustraliaD. BaadeEuropean Organisation for Astronomical Research in the Southern Hemisphere (ESO), Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, GermanyN. SuzukiKavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, JapanAndrew J. ConnollyDepartment of Astronomy, University of Washington, Box 351580, Seattle, Washington 98195-1580, USAF. PatatEuropean Organisation for Astronomical Research in the Southern Hemisphere (ESO), Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, GermanyLifan WangGeorge P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A&M University, 4242 TAMU, College Station, Texas 77843, USAPeter YoachimDepartment of Astronomy, University of Washington, Box 351580, Seattle, Washington 98195-1580, USADavid JonesDepartamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, SpainHisanori FurusawaNational Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanSatoshi MiyazakiNational Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan

2017en

ABI

Аннотация

The detection and simulation of a type Ia supernova with an early, red flash suggests that it formed through detonation of the helium shell of a white dwarf, rather than by collision of the ejecta with a companion star or by merging with another white dwarf. Type Ia supernovae have rather uniform and normalizable light curves, making them suitable for cosmology, yet there remains uncertainty over what paths lead to the explosion. Several years ago a claim was made that a flash seen soon after the explosion was evidence of the shock wave hitting a normal companion star, although most other evidence so far suggests that the explosions arise from the merger of two white dwarfs. Ji-an Jiang and collaborators report observations of a red flash half a day after a type Ia explosion. Their observations lead them to the conclusion that the flash came from the detonation of a thin helium shell surrounding the exploding star. The authors conclude that their finding supports the existence of the previously proposed helium-ignition pathway. 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 white-dwarf 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 normal-brightness 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 interaction8,9,10. 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 less-massive 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 supposed11,12,13,14.

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Идентификаторы

DOI: 10.1038/nature23908

Цитирования и источники

Цитирований: 3Использованных источников: 0

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