Volume 523, November-December 2010
|Number of page(s)||6|
|Section||Stellar structure and evolution|
|Published online||10 November 2010|
Helium-star evolutionary channel to super-Chandrasekhar mass type Ia supernovae
Department of PhysicsShangqiu Normal University,
2 School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, PR China
3 Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
4 National Astronomical Observatories/Yunnan Observatory, the Chinese Academy of Sciences, Kunming 650011, PR China
5 Key Laboratory for the Structure and Evolution of Celestial Objects, the Chinese Academy of Sciences, Kunming 650011, PR China
Received: 2 February 2010
Accepted: 27 July 2010
The recent discovery of several overluminous type Ia supernovae (SNe Ia) indicates that the explosive masses of white dwarfs may significantly exceed the canonical Chandrasekhar-mass limit. Rapid differential rotation may support these massive white dwarfs (WDs). Based on the single-degenerate scenario and assuming that the WDs would differentially rotate when the accretion rate Ṁ > 3 × 10-7 M⊙ yr-1, we performed the numerical calculations for ~ 1000 binary systems consisting of a He star and a CO WD with Eggleton’s stellar evolution code. We present the initial parameters in the orbital period − helium star-mass plane (for WD masses of 1.0 M⊙ and 1.2 M⊙, respectively), which lead to super-Chandrasekhar mass SNe Ia. Our results indicate that for an initially massive WD of 1.2 M⊙, a large number of SNe Ia may result from super-Chandrasekhar mass WDs. The highest mass of the WD at the moment of the SNe Ia explosion is 1.81 M⊙, but very massive ( > 1.85 M⊙) WDs cannot be formed. However, when the initial mass of WDs is 1.0 M⊙, the explosive masses of SNe Ia are nearly uniform, which is consistent with the rareness of super-Chandrasekhar mass SNe Ia in observations.
Key words: binaries: general / stars: rotation / stars: evolution / supernovae: general / white dwarfs
© ESO, 2010
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