arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.09826astro-ph.EPastro-ph.SR
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在自引力盘中尘埃捕获的观测影响

The observational impact of dust trapping in self-gravitating discs

James Cadman, Cassandra Hall, Ken Rice, Tim J. Harries, Pamela D. Klaassen

摘要:

我们提出了一个三维半解析模型的自引力光盘,并包括一个处方的磁盘螺旋臂的灰尘捕获。使用蒙特卡罗辐射转移,我们产生合成ALMA观测这些光盘。在这样做的过程中,我们证明了我们的模型是能够产生观测预测,并能够模拟潜在的自引力盘的实像数据。对于一个光盘产生螺旋结构,将可观察到与ALMA要求光盘的尘埃质量预算是由毫米和厘米大小的颗粒占主导地位。光盘中的晶粒已经增长到晶粒破碎阈值可能满足这一标准,因此,我们预测,签名的引力不稳定性可能是检测到光盘的质量比以前建议的更低。例如,我们发现盘星质量比低至$0.10$的盘能够驱动可观察到的旋臂。在没有发生晶粒生长或晶粒生长已经远远超过晶粒破碎阈值的圆盘中检测子结构变得具有挑战性。我们演示了如何使用我们的模型来检索有关尘埃捕获和晶粒生长的信息,通过多波长观测光盘,并使用不透明度光谱指数的估计。应用我们的光盘模型的埃利亚斯27,WaOph 6和IM Lup系统,我们发现引力不稳定性是一个合理的解释所观察到的子结构在所有3个光盘,如果足够的晶粒生长确实发生。

英文摘要:

We present a 3D semi-analytic model of self-gravitating discs, and include a prescription for dust trapping in the disc spiral arms. Using Monte-Carlo radiative transfer we produce synthetic ALMA observations of these discs. In doing so we demonstrate that our model is capable of producing observational predictions, and able to model real image data of potentially self-gravitating discs. For a disc to generate spiral structure that would be observable with ALMA requires that the disc's dust mass budget is dominated by millimetre and centimetre-sized grains. Discs in which grains have grown to the grain fragmentation threshold may satisfy this criterion, thus we predict that signatures of gravitational instability may be detectable in discs of lower mass than has previously been suggested. For example, we find that discs with disc-to-star mass ratios as low as $0.10$ are capable of driving observable spiral arms. Substructure becomes challenging to detect in discs where no grain growth has occurred or in which grain growth has proceeded well beyond the grain fragmentation threshold. We demonstrate how we can use our model to retrieve information about dust trapping and grain growth through multi-wavelength observations of discs, and using estimates of the opacity spectral index. Applying our disc model to the Elias 27, WaOph 6 and IM Lup systems we find gravitational instability to be a plausible explanation for the observed substructure in all 3 discs, if sufficient grain growth has indeed occurred.

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