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arXiv 0909.0275astro-ph.HEastro-ph.SR
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观看超新星与伴星的碰撞

Seeing the Collision of a Supernova with its Companion Star

Daniel Kasen

摘要:

Ia型超新星和一些核心坍缩超新星的前身被认为是双星系统中的恒星,但几乎没有观测证据证实这一假设。我们认为,超新星喷出物与其伴星的碰撞应该在爆炸后的几小时和几天内产生可检测的辐射。这种相互作用发生在距离约10^11-10^13厘米处,并冲击着撞击的超新星碎片,耗散了动能并重新加热了气体。最初,一些辐射可能会迅速通过影锥的真空区逃逸,产生明亮的X射线(0.1 ~ 2 keV)爆发,持续数分钟到数小时,亮度L ~ 10^44尔格/秒。从更深层的冲击加热喷出物持续的辐射扩散产生了更持久的光学/紫外线辐射,在爆炸后的头几天超过了超新星的放射性光度。这些特征对于俯视电击区域的视角是突出的,或者大约10%的时间。发射的性质提供了一个直接测量恒星之间的距离,因此(假设洛希瓣溢出)伴星的半径。目前的光学和紫外数据集可能已经限制了红巨星的同伴。通过系统地获取许多超新星的早期数据,最终应该有可能凭经验确定祖先系统的参数如何影响爆炸的结果。

英文摘要:

The progenitors of Type Ia and some core collapse supernovae are thought to be stars in binary systems, but little observational evidence exists to confirm the hypothesis. We suggest that the collision of the supernova ejecta with its companion star should produce detectable emission in the hours and days following the explosion. The interaction occurs at distances ~10^11-10^13 cm and shocks the impacting supernova debris, dissipating kinetic energy and re-heating the gas. Initially, some radiation may escape promptly through the evacuated region of the shadowcone, producing a bright X-ray (0.1-2 keV) burst lasting minutes to hours with luminosity L ~ 10^44 ergs/s. Continuing radiative diffusion from deeper layers of shock heated ejecta produces a longer lasting optical/UV emission which exceeds the radioactively powered luminosity of the supernova for the first few days after the explosion. These signatures are prominent for viewing angles looking down upon the shocked region, or about 10% of the time. The properties of the emission provide a straightforward measure of the separation distance between the stars and hence (assuming Roche lobe overflow) the companion's radius. Current optical and UV data sets likely already constrain red giant companions. By systematically acquiring early time data for many supernovae, it should eventually be possible to empirically determine how the parameters of the progenitor system influence the outcome of the explosion.

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