Helium ignition in rotating magnetized CO white dwarfs leading to fast and faint rather than classical type Ia supernovae
Helium ignition in rotating magnetized CO white dwarfs leading to fast and faint rather than classical type Ia supernovae
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DOI：
10.1051/0004-6361/201630121
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发表时间：
2017-01
期刊：
影响因子：
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通讯作者：
P. Neunteufel;P. Neunteufel;S.-C. Yoon;Norbert Langer
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文献类型：
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作者：
P. Neunteufel;P. Neunteufel;S.-C. Yoon;Norbert Langer
CO白色矮星以大约$\sim 10^{-8}\mathrm{M}_\odot/\mathrm{yr}$的速率吸积氦，它们主要基于不包括自转的恒星模型，被认为是许多瞬态天体物理现象的候选祖先，包括Ia型超新星和奇特而微弱的Iax型超新星。在这里，我们研究吸积诱导的自旋的影响，包括随后的磁场产生，角动量输运，和粘性加热的白色矮星演化到氦点火点。我们解决了结构的氦吸积白色矮星模型与一维的拉格朗日流体动力学代码，修改，包括旋转和磁性的影响。我们发现，磁角动量输运，导致准固体旋转，深刻影响的白色矮星模型的演变。我们的旋转较低的质量（0.54 $和0.82 $~\mathrm{M}_\odot$）模型增加了50%以上的质量，点火相比，非旋转的情况下，相反，我们更大规模的模型。此外，我们发现，旋转导致高达10倍的小氦点火密度，除了最低采用的初始白色矮星质量。只有在最低吸积率和大量吸积氦的情况下才能发现10^6\，\mathrm {M}\odot$量级的点火密度。然而，相应地，大质量的施主恒星会以更高的速率转移质量。我们预计氦壳层的爆炸燃烧主要以爆燃的形式发生，并且在$\dot{M}>2\cdot10^{-8}~\mathrm{M}_\odot/\mathrm{yr}$时发生，与白色矮星的质量无关。我们的研究结果意味着氦吸积到CO白色矮星在考虑的利率是不太可能导致CO核心爆炸或经典的Ia型超新星，但可能会产生像微弱和快速的无氢超新星的事件。
Based mostly on stellar models which do not include rotation, CO white dwarfs which accrete helium at rates of about $\sim 10^{-8}~\mathrm{M}_\odot/\mathrm{yr}$ have been put forward as candidate progenitors for a number of transient astrophysical phenomena, including supernovae of Type Ia, and the peculiar and fainter Type Iax supernovae. Here we study the impact of accretion-induced spin-up including the subsequent magnetic field generation, angular momentum transport, and viscous heating on the white dwarf evolution up to the point of helium ignition. We resolve the structure of the helium accreting white dwarf models with a one dimensional Langrangian hydrodynamic code, modified to include rotational and magnetic effects. We find magnetic angular momentum transport, which leads to quasi solid-body rotation, profoundly impacts the evolution of the white dwarf models. Our rotating lower mass ($0.54$ and $0.82~\mathrm{M}_\odot$) models accrete up to 50\% more mass up to ignition compared to the non-rotating case and the opposite for our more massive models. Furthermore, we find that rotation leads to up to 10-times smaller helium ignition densities, except for the lowest adopted initial white dwarf mass. Ignition densities of order $10^6\,\mathrm{g/cm}^3$ are only found for the lowest accretion rates and for large amounts of accreted helium $\gtrsim 0.4\,\mathrm{M}_\odot$. However, correspondingly massive donor stars would transfer mass at much higher rates. We expect explosive He-shell burning to mostly occur as deflagrations and at $\dot{M}>2\cdot10^{-8}~\mathrm{M}_\odot/\mathrm{yr}$, regardless of white dwarf mass. Our results imply that helium accretion onto CO white dwarfs at the considered rates is unlikely to lead to explosions of the CO core or to classical Type,Ia supernovae, but may instead produce events like faint and fast hydrogen-free supernovae.