<p>Double white dwarf binaries are a leading explanation of the origin of type Ia supernovae, but no system exceeding the Chandrasekhar mass limit (1.4 <i>M</i><sub>⊙</sub>) has been found that will explode anywhere close to a Hubble time. Here we present the super-Chandrasekhar mass double white dwarf WDJ181058.67+311940.94 whose merger time (22.6 ± 1.0 Gyr) is of the same order as a Hubble time. The mass of the binary is large, combining to 1.555 ± 0.044 <i>M</i><sub>⊙</sub>, while being located only 49 pc away. We predict that the binary will explode dynamically by means of a double detonation that will destroy both stars just before they merge, appearing as a subluminous type Ia supernova with a peak apparent magnitude of about <i>m</i><sub>V</sub> = −16 (200,000 times brighter than Jupiter). The observationally derived birth rate of super-Chandrasekhar mass double white dwarfs is now at least 6.0 × 10<sup>−4</sup> yr<sup>−1</sup> and the observed rate of type Ia supernovae in the Milky Way from such systems is approximately 4.4 × 10<sup>−5</sup> yr<sup>−1</sup>, whereas the predicted type Ia supernova rate in the Milky Way from all progenitor channels is about sixty times larger. Hence, WDJ181058.67+311940.94 mitigates the observed deficit of massive double white dwarfs witnessed in volume-complete populations, but further evidence is required to determine the majority progenitors of type Ia supernovae.</p>

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A super-Chandrasekhar mass type Ia supernova progenitor at 49 pc set to detonate in 23 Gyr

  • James Munday,
  • Ruediger Pakmor,
  • Ingrid Pelisoli,
  • David Jones,
  • Snehalata Sahu,
  • Pier-Emmanuel Tremblay,
  • Abinaya Swaruba Rajamuthukumar,
  • Gijs Nelemans,
  • Mark Magee,
  • Silvia Toonen,
  • Antoine Bédard,
  • Tim Cunningham

摘要

Double white dwarf binaries are a leading explanation of the origin of type Ia supernovae, but no system exceeding the Chandrasekhar mass limit (1.4 M) has been found that will explode anywhere close to a Hubble time. Here we present the super-Chandrasekhar mass double white dwarf WDJ181058.67+311940.94 whose merger time (22.6 ± 1.0 Gyr) is of the same order as a Hubble time. The mass of the binary is large, combining to 1.555 ± 0.044 M, while being located only 49 pc away. We predict that the binary will explode dynamically by means of a double detonation that will destroy both stars just before they merge, appearing as a subluminous type Ia supernova with a peak apparent magnitude of about mV = −16 (200,000 times brighter than Jupiter). The observationally derived birth rate of super-Chandrasekhar mass double white dwarfs is now at least 6.0 × 10−4 yr−1 and the observed rate of type Ia supernovae in the Milky Way from such systems is approximately 4.4 × 10−5 yr−1, whereas the predicted type Ia supernova rate in the Milky Way from all progenitor channels is about sixty times larger. Hence, WDJ181058.67+311940.94 mitigates the observed deficit of massive double white dwarfs witnessed in volume-complete populations, but further evidence is required to determine the majority progenitors of type Ia supernovae.