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arXiv 0902.4815astro-ph.SRastro-ph.GA
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HD271791:动力学与双星-超新星抛射方案

HD271791: dynamical versus binary-supernova ejection scenario

V. V. Gvaramadze

摘要:

超高速(530-920 km/s)早期B型星HD 271791的大气富含$α$过程元素,表明该星是大质量致密双星系统的前次级组分,其表面在主星超新星爆炸后被核合成产物污染。有人提出,(不对称的)超新星爆炸解除了星系的束缚,而第二颗恒星(HD 271791)以银河系自转方向的轨道速度被释放出来。在这封信中,我们表明,在双星-超新星的框架内解释HD 271791的银河系静止坐标系速度,超新星爆炸的恒星残骸(一个$\la$ 10 Msun黑洞)应该得到一个不切实际的大反冲速度$\geq$ 750-1200 km/s$。因此,我们认为双星超新星的情况是非常不可能的,而是提出HD 271791在母星团致密核心的强烈动力学三体或四体相遇过程中达到了其特有的速度。我们的建议意味着,在相遇的那一刻,HD271791是一个巨大的后超新星双星的成员。

英文摘要:

The atmosphere of the extremely high-velocity (530-920 km/s) early B-type star HD271791 is enriched in $α$-process elements, which suggests that this star is a former secondary component of a massive tight binary system and that its surface was polluted by the nucleosynthetic products after the primary star exploded in a supernova. It was proposed that the (asymmetric) supernova explosion unbind the system and that the secondary star (HD271791) was released at its orbital velocity in the direction of Galactic rotation. In this Letter we show that to explain the Galactic rest-frame velocity of HD271791 within the framework of the binary-supernova scenario, the stellar remnant of the supernova explosion (a $\la$ 10 Msun black hole) should receive an unrealistically large kick velocity of $\geq$ 750-1200 km/s$. We therefore consider the binary-supernova scenario as highly unlikely and instead propose that HD271791 attained its peculiar velocity in the course of a strong dynamical three- or four-body encounter in the dense core of the parent star cluster. Our proposal implies that by the moment of encounter HD271791 was a member of a massive post-supernova binary.

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