arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.07530astro-ph.EPastro-ph.GAastro-ph.SR
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原行星盘吸积率和尘埃质量之间相关的尘埃起源

A dusty origin for the correlation between protoplanetary disc accretion rates and dust masses

Andrew D. Sellek, Richard A. Booth, Cathie J. Clarke

摘要:

最近的观测揭示了原行星盘的吸积率(从紫外连续谱过量测量)与从亚毫米连续谱观测推断的质量之间的相关性。虽然粘性演化模型预测了这样的相关性,但预测值与从狼疮和上天蝎座恒星形成区域获得的数据存在紧张关系;例如,它们低估了吸积率的分散,特别是在较老的区域。在这里,我们认为,由于亚毫米观测跟踪光盘的灰尘,通过明确建模的尘埃颗粒的生长,演变和排放,我们可以更好地理解的相关性。我们表明,湍流粘度与$α\lesssim 10^{-3}$,从光盘由于径向漂移的灰尘耗尽意味着我们可以重现的范围内的质量和吸积率看到的狼疮和上斯科数据集。这个模型的一个结果是,在一个给定的尘埃质量的吸积率的上轨迹不随该地区的年龄。此外,我们发现,内部光蒸发是必要的,以产生最低的吸积率观察。为了复制正确的尘埃质量在光盘分散的时候,我们赞成相对较低的光蒸发率$\lesssim 10^{-9}~M_{\odot}~\mathrm{yr^{-1}}$的大多数来源,但不能区分EUV或X射线驱动的风。有限数量的来源,特别是在狼疮,显示出具有较高的质量比我们的模型,这可能是证据的灰尘或灰尘捕获诱导的子结构的属性的变化预测。

英文摘要:

Recent observations have uncovered a correlation between the accretion rates (measured from the UV continuum excess) of protoplanetary discs and their masses inferred from observations of the sub-mm continuum. While viscous evolution models predict such a correlation, the predicted values are in tension with data obtained from the Lupus and Upper Scorpius star forming regions; for example, they underpredict the scatter in accretion rates, particularly in older regions. Here we argue that since the sub-mm observations trace the discs' dust, by explicitly modelling the dust grain growth, evolution, and emission, we can better understand the correlation. We show that for turbulent viscosities with $α\lesssim 10^{-3}$, the depletion of dust from the disc due to radial drift means we can reproduce the range of masses and accretion rates seen in the Lupus and Upper Sco datasets. One consequence of this model is that the upper locus of accretion rates at a given dust mass does not evolve with the age of the region. Moreover, we find that internal photoevaporation is necessary to produce the lowest accretion rates observed. In order to replicate the correct dust masses at the time of disc dispersal, we favour relatively low photoevaporation rates $\lesssim 10^{-9}~M_{\odot}~\mathrm{yr^{-1}}$ for most sources but cannot discriminate between EUV or X-ray driven winds. A limited number of sources, particularly in Lupus, are shown to have higher masses than predicted by our models which may be evidence for variations in the properties of the dust or dust trapping induced in substructures.

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