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arXiv 0801.1321astro-ph
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Ia型超新星酝酿后期的对流

Convection during the Late Stages of Simmering in Type Ia Supernovae

Anthony L. Piro, Philip Chang

摘要:

在Ia型超新星(SN Ia)中的一颗白矮星(WD)在碳的不稳定点火之后,但在爆炸之前,经历了一个沸腾阶段。在此期间,一个中央对流区的增长,并包括约1 Msun的WD超过一个时间尺度的约1000年,这设置了后续爆炸的热和湍流配置文件。我们研究了这种随时间变化的对流,并总结了一些不同于传统的稳态情况下的关键功能。我们发现,对流区上方的长传导时间尺度和提取的能量加热WD核心导致对流区的顶部边界附近的对流光度和特征速度的减少。此外,对流核心和传导外部之间的成分差异将显著改变该边界的位置。在这方面,我们发现最大的效果,由于完整的22 Ne沉降之前,碳点火。这些影响增加了可能的WD模型的多样性,这可能会改变超新星Ia爆炸的性质。

英文摘要:

Following unstable ignition of carbon, but prior to explosion, a white dwarf (WD) in a Type Ia supernova (SN Ia) undergoes a simmering phase. During this time, a central convective region grows and encompasses ~1 Msun of the WD over a timescale of ~1000 yrs, which sets the thermal and turbulent profile for the subsequent explosion. We study this time-dependent convection and summarize some of the key features that differ from the traditional, steady-state case. We show that the long conductive timescale above the convective zone and the extraction of energy to heat the WD core leads to a decrease of the convective luminosity and characteristic velocities near the convective zone's top boundary. In addition, differences in the composition between the convective core and the conductive exterior will significantly alter the location of this boundary. In this respect, we find the biggest effect due to complete 22Ne sedimentation prior to carbon ignition. These effects add diversity to the possible WD models, which may alter the properties of the SN Ia explosion.

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