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arXiv 1409.7609astro-ph.EP
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碎片盘中大规模碰撞的特征

Signatures of massive collisions in debris discs

Quentin Kral, Philippe Thebault, Jean-Charles Augereau, Anthony Boccaletti, Sebastien Charnoz

摘要:

暴力的随机碰撞事件已被调用作为一个可能的解释,一些碎片盘显示明显的不对称性或具有很大的光度过剩。到目前为止,还没有对这类事件的后果进行彻底的建模,主要是因为将尘埃的动力学和碰撞演化结合起来是一个极端的数字挑战。我们执行的第一个完全自洽的建模的后果,大规模的碎片光盘分裂。我们遵循的碰撞和动力学演化的尘埃释放后,在6 AU的谷神星大小的机构从它的中心恒星分裂。我们调查的持续时间,规模和空间结构的签名留下这样一个暴力的事件,以及其观测可探测性。我们使用最近开发的LIDT-DD代码(Kral等人,2013年),其中处理碎片盘的碰撞和动力演变。主要重点放在破坏性碰撞,开普勒动力学和辐射压力之间的复杂相互作用。我们使用GRaTer软件包来估计系统在不同波长下的光度。谷神星大小的天体在6天文单位处的分裂产生了一个不对称的尘埃盘,通过碰撞和动力学的耦合作用,在几个$10^5$年的时间尺度上均匀化。分裂后的亮度过剩应该可以通过中红外测光法从30 pc的距离上检测到,时间超过了盘的不对称阶段的持续时间(几个$10^5$年)的$\sim 10^6$年。至于不对称结构,我们推导出合成图像的SPHERE/VLT和MIRI/JWST仪器,显示它们应该是清晰可见的,并从10 pc的距离解决。1.6 $μ$ m(轻微)、11.4和15.5 $μ$ m的图像将显示内部椎间盘结构,而23 $μ$ m的图像将显示外部椎间盘不对称。

英文摘要:

Violent stochastic collisional events have been invoked as a possible explanation for some debris discs displaying pronounced asymmetries or having a great luminosity excess. So far, no thorough modelling of the consequences of such events has been carried out, mainly because of the extreme numerical challenge of coupling the dynamical and collisional evolution of dust. We perform the first fully self-consistent modelling of the aftermath of massive breakups in debris discs. We follow the collisional and dynamical evolution of dust released after the breakup of a Ceres-sized body at 6 AU from its central star. We investigate the duration, magnitude and spatial structure of the signature left by such a violent event, as well as its observational detectability. We use the recently developed LIDT-DD code (Kral et al., 2013), which handles the coupled collisional and dynamical evolution of debris discs. The main focus is placed on the complex interplay between destructive collisions, Keplerian dynamics and radiation pressure forces. We use the GRaTer package to estimate the system's luminosity at different wavelengths. The breakup of a Ceres-sized body at 6 AU creates an asymmetric dust disc that is homogenized, by the coupled action of collisions and dynamics, on a timescale of a few $10^5$ years. The luminosity excess in the breakup's aftermath should be detectable by mid-IR photometry, from a 30 pc distance, over a period of $\sim 10^6$ years that exceeds the duration of the asymmetric phase of the disc (a few $10^5$ years). As for the asymmetric structures, we derive synthetic images for the SPHERE/VLT and MIRI/JWST instruments, showing that they should be clearly visible and resolved from a 10 pc distance. Images at 1.6$μ$m (marginally), 11.4 and 15.5$μ$m would show the inner disc structures while 23$μ$m images would display the outer disc asymmetries.

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