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arXiv 0809.3045astro-ph
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超新星Shock Wave同时触发前太阳致密云核坍缩和短寿命放射性同位素注入

Simultaneous Triggered Collapse of the Presolar Dense Cloud Core and Injection of Short-Lived Radioisotopes by a Supernova Shock Wave

Alan P. Boss, Sergei I. Ipatov, Sandra A. Keiser, Elizabeth A. Myhill, Harri A. T. Vanhala

摘要:

在原始陨石形成时存在短寿命放射性同位素(SLRI)如$^{26}$ Al和$^{60}$ Fe的宇宙化学证据要求这些同位素在大质量恒星中合成,然后在$\sim 10^6$年内并入陨石。长期以来,人们一直假设超新星冲击波将SLRI输送到太阳系前的致密云核心,引发云的坍塌,并注入同位素。以前的数值计算表明,当激波和稠密云核假定在$\sim 10$ K下等温时,这种情况是合理的,但当压缩加热到$\sim 1000$ K时,这种情况就不合理了。我们在这里首次表明,当计算与FLASH2.5自适应网格细化(AMR)流体动力学代码,20公里/秒的冲击波确实可以触发崩溃的1 $M_\odot$云,同时注入冲击波同位素到崩溃的云,提供冷却的分子种类,如H $_2$ O,CO $_2$,和H $_2$包括在内。这些计算意味着超新星触发假说是在太阳系形成期间提供SLRI的最可能机制。

英文摘要:

Cosmochemical evidence for the existence of short-lived radioisotopes (SLRI) such as $^{26}$Al and $^{60}$Fe at the time of the formation of primitive meteorites requires that these isotopes were synthesized in a massive star and then incorporated into chondrites within $\sim 10^6$ yr. A supernova shock wave has long been hypothesized to have transported the SLRI to the presolar dense cloud core, triggered cloud collapse, and injected the isotopes. Previous numerical calculations have shown that this scenario is plausible when the shock wave and dense cloud core are assumed to be isothermal at $\sim 10$ K, but not when compressional heating to $\sim 1000$ K is assumed. We show here for the first time that when calculated with the FLASH2.5 adaptive mesh refinement (AMR) hydrodynamics code, a 20 km/sec shock wave can indeed trigger the collapse of a 1 $M_\odot$ cloud while simultaneously injecting shock wave isotopes into the collapsing cloud, provided that cooling by molecular species such as H$_2$O, CO$_2$, and H$_2$ is included. These calculations imply that the supernova trigger hypothesis is the most likely mechanism for delivering the SLRI present during the formation of the solar system.

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